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Selective Color Boosting (Photoshop Tutorial)

|Tutorials|5 Comments

In this astrophotography image processing tutorial, I will explain an easy way to selectively boost the colors in your image. I like to call the technique “selective color boosting“.

Increasing the saturation of your deep-sky object can bring out the true beauty of your subject, and better showcase the contrasting elements of the nebula or galaxy.

The amount of “boosting” is up to you of course. Some prefer bright, vibrant colors, while others prefer a toned-down “natural” look. I’d like to consider my images to be somewhere in the middle. 

The definition of a “true-color” image varies, but the techniques described in this tutorial are generally accepted in the astrophotography realm. 

Selective Color Boosting for Astrophotography

The Triangulum Galaxy in RGB (Dedicated Astronomy Camera).

Long exposure astrophotography can reveal the colors of all deep-sky objects and galaxies. By exaggerating these colors through post-processing, we can increase the impact of the image.

In this tutorial, I’ll use Adobe Photoshop to accomplish our tasks. This software includes countless tools to perform the finishing touches on your images. (See the rest of the astronomy and astrophotography software I use).

I have also found it to be a fantastic start-to-finish image editor, with the help of a few third-party plugins of course. But we’ll get to that in a minute.

The example images in this article were captured using a variety of cameras, from an astro-modified DSLR camera to a monochrome CCD camera. The color boosting methods I describe will work for all color images, whether they are broadband RGB, LRGB, narrowband, bi-color, etc. 

The data used in this tutorial was registered, stacked, and calibrated in DeepSkyStacker first. If you need help with the pre-processing stages of deep-sky astrophotography, be sure to check out my premium image processing guide

For an overview of this process, please watch my video tutorial on YouTube:

How to Boost the Colors in Your Astrophotography Images

Astrophotography is a broad term and covers a wide variety of disciplines from wide-angle Milky Way nightscapes, to high-magnification planetary imaging. 

The methods of boosting color discussed below are most applicable to deep-sky imaging of nebulae and galaxies, but can also be applied to all forms of digital photography.

In a nutshell, you need to carefully isolate the areas of color that you wish to enhance, and leave the rest of the image alone. 

If you globally increase the saturation of your astrophoto, you run the risk of intensifying noise, color-mottling, and other nasty surprises hiding in your data. 

For example, in my image of the Whirlpool Galaxy shown below. I wanted to focus on boosting the colors of the areas of pink hydrogen inside of the spiral arms, without oversaturating the blue areas of the galaxy. 

whirlpool galaxy

The Whirlpool Galaxy in LRGB (Mono CCD and telescope).

The same selective color boosting method can be used on a wide-angle nightscape image too. The most challenging part of the process is the selection itself.

In the example image below, I again carefully isolated the areas of pink hydrogen emission nebulae. I was able to increase the saturation of these areas and brighten them with a careful mask selection. 

Truth be told, I could have done a better job at masking the darker areas of the night sky, but I think you get the idea. 

The Milky Way

The Core of the Milky Way. Canon DLSR and a wide-angle lens. 

As you can see, this technique gives you full control over the amount of saturation in your image in each area. The key concept is that you’re being very specific about which areas of color are boosted.

A basic saturation slider adjustment to the image as a whole will degrade the quality of your image significantly. 

With some inspiration to get your creative juices flowing, let’s get into the nuts and bolts of the process.

When to Start Boosting Colors

The timing of these actions on your image is up to you, but I highly recommend leaving it until the end. 

After the pre-processing stages (DeepSkyStacker, Astro Pixel Processor, etc.)

The first few steps you take towards processing your image should focus on balancing the RGB levels in the histogram and applying basic curve adjustments that bring up the signal.

Here is a basic image processing workflow timeline that I generally follow:

  1. Levels Adjustment
  2. Curves Adjustment
  3. Balance Levels
  4. Neutralize Background
  5. Curves Adjustment
  6. Star Color Adjustment
  7. Star Minimize
  8. Selective Color Boosting
  9. Noise Reduction
  10. Sharpening

You may want to make some less dramatic stretches to your colors along the way, but leave the selective color boosting method until the end of your workflow. 

The reason for this is that your image won’t be in a state that portrays what the final colors will look like until the end of your workflow. 

Soul Nebula

The Soul Nebula captured using a DSLR camera and a small refractor.

How to Select Specific Colors

There are two selection tools in Adobe Photoshop that allow you to isolate specific areas of your image. One (Color Range) makes an early, rough selection based on your input. The second (Select and Mask), is much more powerful and allows you to refine a detailed mask over your image.

With a careful selection and masking process, you can then create a new adjustment layer to increase saturation and vibrance. The same powerful masking technique also allows you to carefully adjust the highlights on your image, noise, sharpening, and much more.

In the image of the Pleiades shown below, I selected the outer nebulous regions of the object to increase saturation and bring up the midtones. 

new adjustment layer

At the heart of this image processing technique is the Color Range tool. This magnificent tool was introduced way back in Adobe Photoshop 3.0, and photographers have been enjoying it ever since. 

Select Color Range

The Color Range tool in Photoshop is an effective way to start the selection process. I like to use this tool to create a rough mask that can later be refined.

You can find this tool in the main menu under Select > Color Range…

select color range

The Color Range Tool is under the “Select” heading in the main menu.

This opens up a new dialogue box with a number of options to choose from. The drop-down menu at the top labeled “select” is where you will need to decide which method you would like to use to quickly grab the details you’re interested in.

I find “sampled colors” to be the most effective because you can use the eyedropper tool to manually point to the colors in your image you would like to enhance. 

The “highlights’ selection method is also very useful, as this is often the best way to separate your deep-sky subject (and stars) as a whole from a background sky.

sampled colors

“Sampled Colors” lets you manually pick the color range in your image.

No matter which selection method you use, you’ll want to do a basic refinement of your selection using the preview window. Make sure the “Selection” option is ticked during this stage.

In my image, I want to select the blue areas of the Trifid Nebula, so I can apply a targeted adjustment to this element only.

You simply need to click the eyedropper on the color range you would like to isolate, and the preview window will display a rough mask over these regions in the preview window. 

You can also change the selection preview dropdown menu to “Grayscale” for a live preview of your upcoming mask on your full-size image.

color range selection

The preview window provides a rough idea of your initial selection (change the selection preview to grayscale to see a full-size image).

You can adjust the “fuzziness” and “range” sliders to increase the selection of the mask. Make sure that you have the “localized color clusters” checkbox ticked off for full control. 

The eyedropper with the “+” and “-” icons next to them allows you to add or subtract from your selection, but they are a little too unrefined to be effective for our purposes.

The point of this step is to isolate the areas of color in your image that you wish to boost the colors in. Don’t worry about getting too specific at this point, as we will refine the mask substantially in the next step. 

When you are happy with your rough color range selection, you can click the OK button. Now you should see the “marching ants” selection on your original image, which is not a very helpful indication of our selection.


Our initial color range selection is applied. 

The Select and Mask Tool

When it comes to processing astrophotography images, the Select and Mask tool is probably the most important tool in all of Photoshop. To really get the most out of your images, isolating one element from another is essential.

The Select and Mask tool allows you to refine your selections with an extremely robust set of adjustment options. Learning how to harness the power of this feature will most certainly improve your astrophotography image processing skills.

I will use the terms “selection” and “mask” interchangeably, as they are essentially the same thing. When we create a “layer mask” it just means that we are isolating a portion of the image to either be left-alone or targeted for adjustments.

With your original Color Range selection still active, navigate to the main menu, and click Select > Select and Mask

The Select and Mask tool. 

An important step to remember here is that you will want to make sure your original, rough, color range selection is active (as indicated by the marching ants on your image) before invoking the Select and Mask feature. 

There is a lot going on in the Select and Mask dialogue box. Below, I have provided an overview of the key adjustment sliders you’ll want to pay attention to when processing a deep-sky image. Click the image for a larger version. 

select and mask astrophotography

The purpose of this tool is to allow you to make precise refinements to your selection, and provide a clear indication of where this mask will be applied. 

There are several options to choose from when it comes to the way the mask is displayed on your image. The view modes are as follows:

  • Onion Skin
  • Marching Ants
  • Overlay
  • On Black 
  • On White
  • Black and White
  • On Layers

In my eyes, the Black and White view mode is by far the most useful. You may see the Onion Skin view mode appear by default, which I have found to be the second-best option from this list. 

Adjusting the Sliders to Refine Your Mask

The three most important sliders to adjust in the Select and Mask dialogue box are Contrast, Feather, and Shift Edges. A balanced approach between all three will yield the best results.

The Contrast slider is used to further separate your masked area from the rest of the image. With the Black and White view mode active, increasing the Contrast Slider will result in a more defined “shape” of the color range, with less of a transition area between the highlights and shadows.

Photoshop settings

The important adjustment sliders in the Select and Mask tool.

The Feather slider is the most important of them all because this creates a smooth transition between the edges of your mask and the background. Aim for super-soft edges around your targeted area to avoid harsh edges between your manipulated elements. 

The Shift-Edges slider is useful for expanding the area of your selection mask overall, retaining any feathering settings you have put in place. Between these three adjustment sliders, you should be able to create the ultimate layer mask for your image.

Note: You can use the brush tool (set to your desired width and softness) to remove specific areas of your selection. On a PC, just hold down the Alt key to subtract from the image when painting with the brush tool.

Accept the Mask and Create and a New Adjustment Layer

The default action that takes place after hitting OK on the dialogue box is to output to a selection. This will display the marching ants view overlay on your image. 

From here, you will want to create a new adjustment layer to apply your desired saturation boost and any other effects. For increasing color, you’ll want to choose the Vibrance… adjustment layer.

vibrance adjustment layer

The advantage of this procedure is being able to see a full-size preview of your image with your targeted adjustments to the selection happening in real-time. 

You may want to choose “output to: new layer“, as this will essentially accomplish the same result.

In this scenario, you would simply edit the new layer with your desired effects rather than as a new adjustment layer. 

Selective Color Boosting

By now you should have a solid understanding of how the color range selection tool works, and why it’s important to isolate the specific areas of your image that you want to manipulate.

With a well-defined selection mask placed over your image (remember, the white areas will be affected, the dark will not) you can begin to increase the vibrance and saturation of the important colors of your nebula or galaxy.

In case you’re getting a little lost in the order of things, here is a step-by-step path to get you up to speed:

  1. Select > Color Range
  2. Use Sampled Colors from Dropdown Menu
  3. Place the eyedropper on the color range you would like to boost
  4. Adjust the fuzziness and range sliders to roughly isolate these colors in the image
  5. Click OK to confirm your rough selection
  6. Open Select > Select and Mask to further refine your selection
  7. Use the Feather, Contrast, and Shift Edges sliders to create a smooth mask on your subject
  8. When you are happy with the selection (remember, no hard-edges!), click OK
  9. With the selection active, click Layer > New Adjustment Layer > Vibrance

The following illustration shows what your screen should look like at this stage. The new adjustment layer is the top-most layer, which ensures that your edits will be seen as you make adjustments. 

boost saturation

Adjust the vibrance and saturation sliders to your selected area.

Now, you can adjust the vibrance and saturation sliders to increase the color of your selected area. Pay close attention to your image at a glance at this stage.

Remember, drastic changes made to isolated areas of the image run the risk of looking unnatural. This is another reason why creating a mask with a soft, feathered edge is very important.

Any areas where the mask stops abruptly may appear odd in your final result. The more you “push” the data, the more pronounced this effect becomes. 

In the example below, I chose to increase the saturation of the warmer colors in the image. The Pinwheel Galaxy appears as a very cool blue color when stretched, and I wanted to contrast these cool areas with the warmer core of the galaxy. 

Pinwheel Galaxy

In this image of M101, Selective Color Boosting was used to keep the core warm, and the spiral arms cool.

There are no rules when it comes to the exact saturation settings you should use to enhance the color of your image.

I tend to bump the sliders up to about 15-20, depending on the deep-sky object, and the desired look I am going for. Once you are happy with the amount of boosting to the saturation and vibrance you have applied, you can simply close the properties window.

The new adjustment layer will sit on top of the other layers in your image. From here, you can save the file with the layers intact (.PSD file), or simply flatten the image and save it as a JPEG or TIFF. 

saturation settings

Typical vibrance and saturation settings for a deep-sky image.

Adjusting Color Balance, and Photo Filters

Since you have gone to the trouble of creating a highly selective layer mask, why not use it to make other color enhancements as well? 

In certain situations, creating a color balance adjustment layer is helpful. You can gently pull the colors towards a cooler or warmer result as desired. 

If bumping up the saturation and vibrance sliders don’t achieve the look you are going for, you can also try a specific photo filter

warming filter

The color balance and photo filter adjustment layers can be useful for certain looks.

I have found the warming filter to be useful for enhancing star colors, and the cooling filter to be useful for a natural background sky. In all scenarios, you’ll want to mask the area that you are applying the color filter to. 

Adjust the Opacity of the Adjustment Layer

Remember, you can always adjust the opacity of your new adjustment layer, and tone down the amount of saturation in your image.

If you feel like you have overdone it, just bring the opacity slider down to about 25%. Turn the layer visibility on and off to observe the subtle enhancement this technique makes to your astrophoto. 

I usually make my vibrance/saturation layer rather aggressive, and then bring the opacity slider down to about 50% to “normalize” things a little bit. 

You will have to practice the selective color boosting technique on a few images to really get a feel for it. The more types of images you perform this task on, the more comfortable you’ll feel.

Remember, this method can be useful for all types of astrophotography, not just deep space nebulae and galaxies. 

nightscape photography

Final Thoughts and Advice

If you were able to follow along with this tutorial, you should have a good feel for the Select and Mask tool, and its power. You can use the same selection process to perform other tasks on your image, from noise reduction to sharpening.

Although the examples in the tutorial focused on selective color boosting nebulae and galaxies, the technique works exceptionally well when processing star colors, too.

In this case, you would want to mask out the stars in the image on their own, so you have full control over their saturation without disrupting the rest of the image. 

For the wide-field view of the Eagle Nebula shown below, I isolated the stars using the “highlights” color range mode and increased their saturation independently from the rest of the image. 

star colors

The colorful stars surrounding the Eagle Nebula.

If you are unsure about how far to take your image, in terms of boosting saturation, I find it useful to use a reference image. I often search for APOD images of my target and see the direction that other amateur and professional astrophotographers have chosen to steer the image in.

If I could offer one more piece of advice, I would like to remind you why you began your journey in astrophotography: enjoyment. Adjust your personal images in whichever way you think looks best.

If you have found this image processing tutorial useful consider purchasing my premium astrophotography image processing guide

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Topaz Labs DeNoise AI Review

|Image Processing|12 Comments

The goal of Topaz Labs DeNoise AI is to reduce digital image noise while preserving detail and increasing image sharpness. If you’re no stranger to astrophotography image processing, that almost sounds too good to be true.

I was skeptical of the application myself but now find myself using it in some capacity for every astrophoto I process. I believe that Topaz Labs DeNoise AI is a powerful tool that amateur astrophotography enthusiasts should consider adding to their bag of processing tricks.

In fact, I even added a new section about Topaz DeNoise AI in my premium astrophotography image processing guide. I have no interest in spending time learning and writing about tools with a short shelf-life, and I don’t see myself shying away from DeNoise AI anytime soon. 

Until discovering this photo noise reduction software, I typically used the built-in noise reduction features of Adobe Camera Raw. This works well enough but is not nearly as reliably effective as the one-click, automatic noise reduction function of DeNoise Ai.

Whether you use Topaz Labs DeNoise AI to batch process a handful of night sky images in Lightroom or use it to subtly control the noise in your deep-sky images in Photoshop, this advanced learning software feels like it was built for astrophotography.

If you have experience using other noise reduction tools such as Skylum Luminar, Noise Ninja, DXO Prime, or any other of the many options available, please let me know how my results with DeNoise AI compare in the comments. 

Photo noise reduction software

Download: Topaz DeNoise AI 30-Day Trial

Topaz Labs DeNoise AI Review

As you may already know, noise can be a big problem for amateur astrophotography, especially when using a DSLR or mirrorless camera with a high ISO setting. I have personally been battling noise in my astrophotography images for nearly a decade. 

Even with great image acquisition best practices, lots of data, and a cool astronomy camera, you will likely still need to minimize the noise in your image at some point in the image processing stages of astrophotography.

In general, the tricky part of applying a noise reduction filter to your image is the possibility of detail loss, which can create a blurry looking image.

Noise Reduction

I originally shrugged off anything to do with this software due to the fact that I am a diehard Adobe Photoshop fan. I realize that many people are not willing to fork out the dough for a Creative Cloud subscription, but I certainly am. I’ve been using Adobe Software for nearly 20 years, and get full value out of my subscriptions to Photoshop and Premiere. 

I’ve used many third-party plugins with Photoshop in the past (see the resources page for a few that stand out), but the Topaz Labs DeNoise AI plugin is different. I don’t believe any of the software I have installed in the past actually tapped into the benefits of artificial intelligence that continues to get better over time. 

Topaz Labs DeNoise AI allows you to download a full-featured 30-day trial, so you’ve got nothing to lose. I took advantage of this opportunity, fell in love with the tool, and gladly forked out the cash for a lifetime license of the software. 

In this post, I’ll explain how to incorporate Topaz DeNoise into your astrophotography image processing workflow, and why I think it’s a no brainer for anyone that spends as much time photographing space as I do.  

Is it a Photoshop Plugin?

First things first, you’ll need to install the software on your computer. Topaz DeNoise is available for both Mac and PC operating systems. For better or for worse, I am a diehard PC user, and I installed the lightweight software on my Windows 10 desktop.

I am using Topaz Labs DeNoise AI as a Photoshop 2020 plugin exclusively. Users have the option of using the DeNoise AI as a standalone program, or a plugin in Adobe Lightroom or, of course, Topaz studio.

I don’t typically utilize the batch processing feature of Topaz DeNoise AI and prefer to invoke the tool on a per-image basis when noise reduction is needed.


A before/after example of Topaz DeNoise AI on the Orion Nebula

As far as astrophotography goes, I am sure that most users will use the tool as a Photoshop plugin as I do, during the post-processing stages of their workflow. However, daytime photographers may find the tool handy when editing photos in Lightroom.

This is one of the biggest reasons why I was able to introduce the Topaz Labs DeNoise AI into my existing workflow so effortlessly. I simply run the tool on a new layer in Photoshop just as I would with any other Photoshop filter or external plugin.

Topaz Labs DeNoise is available as a plugin for the following applications:

  • Adobe Photoshop
  • Adobe Lightroom
  • Corel PaintShop Pro
  • Serif PhotoPlus

I absolutely love the simplicity of the user interface (UI). At its core, the software has to be good at one thing, and that’s effective noise reduction. The minimalist interface, large buttons, and massive preview window make it very easy to see what’s taking place. 

DeNoise AI Photoshop Plugin

The Problem with Noise in Astrophotography

Many factors come into play when assessing the reasons why your astrophoto is so noisy. Sensor design, size, and the camera settings used when the photo was taken are the most obvious. 

Noise is the unwanted, randomly placed “grain” caused by your digital camera’s sensor. Noise often increases when using higher ISO settings, and appears as uneven color and grainy pixels distributed throughout your image.

It is most noticeable in solid areas of color, especially darker areas such as a black night sky. This can be a major problem for astrophotography, as our images usually have plenty of dark sky areas in them, surrounding the subject. 

When you attempt to brighten your astrophoto to reveal faint structures of nebulae, stars, and galaxies, you also risk increasing the presence of noise. 

When you zoom in on your image at 100% magnification, don’t be surprised to find grainy, random color specks, and overall inconsistency in the darker areas

The two ugly sides of the noise equation are Luminance Noise and Chrominance Noise. This article will help you understand what causes noise in digital photography.

The Signal-to-Noise Ratio

The best way to reduce noise in your astrophotography images is to improve the signal-to-noise ratio (SNR). Meaning, capture as many sub-exposures as possible and integrate the data using software such as DeepSkyStacker, Astro Pixel Processor, or PixInsight.

By nature, long-exposure photography in dark situations is just asking for noise. But amateur astrophotographers have found ways to overcome this issue to a large extent through image stacking, and calibration frames such as dark frames

Yes, this practice is essential for creating a quality astrophoto, but sometimes it just isn’t enough. I’ve found myself in situations where over 5 hours of data were collected with my DSLR camera, and the healthy SNR still wasn’t enough to achieve an image with a smooth, sharp background. 

A neutral, smooth background sky is one of the toughest challenges in the world of astrophotography image processing. Finding ways to isolate this element of the image, and tame the noise and unsightly artifacts found within it is essential. And this is exactly where Topaz Labs DeNoise AI shines. 

The chroma noise reduction feature is especially handy in these situations, but monitoring your image as a whole during this step is a must. I can’t stress enough the fact that masking (see my Select and Mask tutorial), isolating, and defining each element of your astrophotography image is paramount for success.

How to Use Topaz Labs DeNoise AI

The software is simple to download and install, and automatically integrates itself into Adobe Photoshop. There is no need to drag-and-drop specific files into the program folders as you do with other third-party plugins. 

At its core, DeNoise AI is a photo noise reduction software. More specifically, the tool was designed to enhance sharpness, remove chroma noise, and eliminate noise without losing details. The official Topaz DeNoise user guide includes a complete list of primary functions.

It’s safe to say that astrophotography was not the primary intended use for Topaz DeNoise AI, but it happens to benefit from it a great deal. The horizontal and vertical banding lines, black level correction, and high ISO image recover features are the most utilized aspects.

To run the plugin in Photoshop, you simply need to navigate to the Filter drop-down menu. At the bottom of the list, you should see Topaz Labs > Topaz DeNoise AI. If this option is greyed out, make sure your image is in 16-bit or 8-bit mode (it will not work in 32-bit mode). 

Upon activating the plugin, you’ll be delivered with a large preview window of the image with the noise reduction effects applied, next to your original (split view). 

preview image

You’ll notice that the software interface presents you with two processing models: DeNoise AI and AI Clear. You’ll want to use the DeNoise AI option, as it is the newer feature and tends to work a lot better than the previous AI Clear mode (which was a feature of the original Topaz Studio).

With the DeNoise AI model selected, you can now select your noise reduction mode. I recommend trying out the “auto” mode on your image, as applying this filter to your picture often does a fantastic job (you can thank millions of AI training images for this).

DeNoise AI user interface

The Manual Mode gives you much more control over the noise reduction filter. You can independently adjust the following sliders to your taste:

  • Remove Noise
  • Sharpen
  • Recover Original Details

Best Practices for Astrophotography Images

Deep-Sky Astrophotography

I primarily shoot deep-sky astrophotography images through a telescope, of distant nebulae and galaxies. For these types of photos, Topaz DeNoise AI is an incredible tool to help remove an uneven background sky. 

The chroma noise reduction slider is especially handy when dealing with an astrophoto with a noisy, unevenly colored background sky.

I’d still mask the nebula or galaxy (and in most cases, the brighter stars) in the image before running Topaz DeNoise, but you can count on the DeNoise filter to improve the ugly luminance and chroma noise in the darker regions.

The power of DeNoise Ai in these situations should not be understated. Astrophotographers (particularly ones shooting with a DSLR camera) have been dealing with this problem for many years, and this software handles it better than any other tool I’ve ever used. 

nebula example

Nightscape Photography

I’ve stated how impressive the tool works for images of nebulae and galaxies, but what about a wide-angle shot of the Milky Way? Well, I tested that scenario on an image of the Milky Way I captured under dark skies with a Rokinon 14mm F/2.8 lens. 

As you can see, Topaz Labs DeNoise AI did a fantastic job of preserving important details of this demanding image, while making a noticeable improvement to the overall aesthetics by smoothing out grainy areas of the picture.

DeNoise AI example on the Milky Way

I don’t think that this post-processing tool can totally make up for an image shot using an ISO setting that was too high, but it may be able to save some of the images you originally thought were just too noisy to share.

Usage Tips

The best part about Topaz Labs DeNoise AI is how simple it is to use. Most often, I utilize the “auto” feature of the plugin and apply the default AI noise reduction amount to my image. It’s best to apply this action to a new layer on top of the image, so you can adjust the opacity and overall impact of the effect.

The “Auto” Noise Reduction setting works surprisingly well most of the time. 

Usually, I will apply the DeNoise AI layer at approximately 65% over the entire image. Then, it is wise to monitor any negative changes to the look of the stars in your image. I have found that sometimes the DeNoise AI plugin will change the shape of small-to-medium-sized stars, and even create “holes” in them.

To avoid this scenario, you have a few options. You can create a layer mask in Photoshop to protect all of the stars in the image before running Topaz Labs DeNoise AI.

You could also (this is my favorite method), apply the DeNoise action to the entire image globally, and then use the eraser brush (set to the opacity, softness, and size of your choice) and carefully reveal each element in the image from beneath the DeNoise layer.

This may seem like a painstaking process, but I have found this way to offer the most control.

california nebula

DeNoise AI has helped me revive some of my noisier images from the archives.

AI-Powered Noise Reduction

I know that most of you are no stranger to the concept of machine learning. Essentially, the team at Topaz Labs trained an AI model using specific filters to produce remarkable results.

This process is well-beyond my capabilities and understanding as an amateur astrophotographer, but that doesn’t mean I can’t leverage this AI power to create better images.

This article explains how Topaz Labs used millions of clean and noisy images to train the software to understand what to remove (chroma and luminance noise), and what not too (important details, colors, and sharpness). 

To witness this AI technology in action, all you need to do is appreciate the automatic results of the DeNoise AI plugin on one of your noisy astrophotos. 

landscape images

System Requirements

A number of people have reminded me that you should consider the system requirements of this software before purchasing the plugin.

I am currently using Topaz DeNoise (version 2) on my Windows 10 Desktop with an Intel Core i7-9700K processor @ 3.60 GHz, and 16 GB of RAM. The Graphics Card is an NVIDIA GeForce RTX 2060.  

On my machine, the DeNoise AI preview window updates really fast and applying the filter takes about 1-2 seconds. However, slower machines will inevitably bring this process to a crawl, so I looked into the system requirements Topaz recommends.

CPU Minimum

  • Intel i5 or equivalent (3.0GHz and above)
  • AMD Ryzen 5 or equivalent (3.0GHz and above)

CPU Recommended

  • Intel i7 or greater (4GHz and above)
  • AMD Ryzen 7 or greater (4GHz and above)

Graphics Card Minimum

  • NVIDIA 2GB of dedicated VRAM (GT 740 or greater)
  • AMD 2GB of dedicated VRAM (Radeon 5870 or greater)

Graphics Card Recommended

  • NVIDIA 4GB of dedicated VRAM (GTX 970 or greater)
  • AMD 4GB of dedicated VRAM (Radeon RX 460 or greater)


  • Minimum: 8GB
  • Recommended: 16GB
  • Optimal: 32GB

If your computer meets the recommended requirements for the software, Topaz Labs states that ‘Users should experience no performance issues, though slowness may occur with large files”. I have found this to be true in my experience using the software on a fast Windows 10 PC. 

Final Thoughts

Processing astrophotography images can be challenging, especially when you haven’t collected the amount of data you hoped to. It would be nice to acquire 10+ hours of exposure time on each target, but that isn’t realistic for a lot of people.

Topaz Labs DeNoise AI allows you to make the most of your data integration. If you’re sitting on a handful of images that aren’t quite “post-worthy”, run them through DeNoise AI and give them a second look. 

One of the most exciting parts of this experience, for me, was going through some old astrophotos and seeing which ones I could potentially recover. Tools like DeNoise AI have the ability to breathe new life into old projects.

To justify the cost of a new software tool, you need to receive a lot of value from it. I truly think that you will enjoy using Topaz Labs DeNoise AI on your astrophotos now, and in the future. 

M82 Galaxy

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Remove Gradients in Your Astrophotos with Photoshop

|Tutorials|12 Comments

Adobe Photoshop is the preferred weapon of choice for many astrophotographers of varying levels of experience.  The intuitive user interface and limitless image processing capabilities make it a real contender in the astrophotography world.

The seamless integration with the .RAW image files produced by a Digital Camera makes Photoshop an attractive choice for photographers using popular Canon and Nikon DSLR’s.

I have included a section on gradient removal in my premium astrophotography image processing guide for those interested. 

It continues to be my personal favorite tool for processing astrophotography images.

The M78 nebula in OrionWhether you are brand new to astrophotography image processing, or a seasoned veteran, an uneven field in your image is something that every astrophotographer will deal with at some point.

The steps I will discuss below can be done in Photoshop without using any additional plugins. However, I strongly recommend investing in the Astronomy Tools Action Set, and Gradient Xterminator.  They are well worth the expense and can make a monumental difference to your images.

This Photoshop tutorial involves the following:

  •   Assessing your uneven field
  •   Removing the DSO from your image
  •   Creating a synthetic flat frame
  •   Subtracting the flat frame from your image


An Effective Photoshop Technique for Removing Gradients

One of the most time consuming and frustrating stages of your image processing workflow can be dealing with gradients.  Your background sky goes from a dark blue to pink as the encroaching glow of city light pollution stains your image.  Luckily, there is an extremely useful and effective method for removing gradients using Photoshop.

This method involves creating a synthetic flat frame and subtracting it from your original image.

Quickly correct your uneven field

The method you’ll see me use in the video below is a very popular way to remove gradients using Photoshop.  Variations of this technique have been used by amateur astrophotographers for years.  I do not take credit for this method.  Like almost everything else I have learned about this hobby, I picked this up by watching and reading countless image processing tutorials shared by others.

Video: How to Remove Gradients in Photoshop:

This technique works better on some deep-sky images better than others.  Large targets such as nebulae that fill the entire frame will be difficult to tackle using this process.  In my example, the Leo Triplet of galaxies worked very well, as they are surrounded by a large area of surrounding space.

Assessing the Data

  1. Start by opening up your final stacked image.  I use DeepSkyStacker to register and stack all of my image frames.
  2. Crop your image to remove the stacking artifacts and overlapping frames.
  3. Convert the image from 32bit to 16 bit, to open up further editing options in Photoshop.
  4. Perform a quick levels adjustment, bringing the left-hand slider up against the data on the histogram.
  5. Make a curves adjustment, pulling the details contained in your deep-sky object forward.
  6. By now, you should have a good idea of how bad the vignetting and color gradients are in your image.


Gradient issues in a astrophotography image

A curves adjustment will show the uneven field

Removing the DSO from the image

Now comes the fun part.  This is where you either have the option of running a third-party plugin such as Gradient XTerminator or tackling the issue yourself.  It’s beneficial to learn this method of removing gradients in photoshop for all types of astrophotography including wide field Milky Way shots.

  1. First, copy your original image layer and paste it on top.  Name it “Gradients”
  2. Copy this layer to a new image. Select All > Copy > File > New > Paste.
  3. On the new image that was just pasted, remove the deep-sky objects from the field of view.

This can be done in various ways, but I prefer to use the healing brush.  The important part to remember is that we are only interested in the color information of the background sky.  We don’t want to change the data found in the deep-sky objects themselves.  See this in action in the video above.


Using the healing brush in Photoshop

Remove the DSO using the healing brush

Creating a Synthetic Flat Frame

Now that we have a version of our image without our deep-sky object(s), we can correct the uneven field in the background sky.  At this point, you may also want to remove any bright stars that may negatively affect the resulting synthetic flat frame.

Richard Hum had this to say on YouTube:

What I usually find helpful is to use Select > Color Range > Highlights to select the stars, and then do a content-aware fill. I find it works better than not removing the stars and just doing dust and scratches. You can use the Select and Mask tool to refine your selection mask.

  1. Now, we need to blur the details of our copied DSOless image. Choose Filter > Noise > Dust and Scratches.
  2. For my camera’s resolution in the example, a Radius value of 80 pixels was used, and a Threshold of O.
  3. You should now see a blurred version of the background sky, with an evident uneven field.


creating a synthetic flat frame

Our synthetic flat frame

Applying the Flat frame to your Image

  1. Now, go back to your original image, and make sure you have the “Gradients” layer we created selected
  2. Next, choose Image > Apply Image.
  3. From the Source drop-down menu, select the copied, blurred image we just created. (Untitled-1)
  4. From the Blending Mode dropdown, select Subtract.
  5. Leave the Opacity at 100%, and set the Offset to 30 and hit, OK.


Deep sky astrophotography

Your new and improved image

Your new image with the gradients layer on top should look much better.  The “Gradients” layer we created can be scaled back by using the Opacity slider on the layer.  You may not need to use this layer at 100% to completely correct your gradient issues, but expect to have it set to between 80%-100% in most cases.

This layer can be toggled on and off to review and inspect the improvements to your image.  If necessary, you can go back and test some of the variables including changing the Radius value, and/or removing the stars before blurring the frame.

From this point, you can go about your image processing as you normally would, with a much improved, even background sky.

Widefield images captured with my camera lens suffer from horrible vignetting in my backyard.  The gradient removal technique above was used on this image of the Orion constellation to correct the background sky:

Orion constellation

The Orion constellation from my backyard

Try this method on some of your existing widefield images that suffer from a gradient in the background sky.  An uneven field is a common problem in almost all astrophotos, so mastering this technique will come in handy in your future endeavors.

Did you know you can sell your astrophotos as stock photography?  I have sold several of my images on Shutterstock over the past 3 years.  View my portfolio.

You can stay up to date with the latest images and information on the AstroBackyard Facebook page, or by following me on Twitter and Instagram.

Until next time, clear skies!

Related Posts

Astrophotography Tutorials – AstroBackyard

Astrophotography Tutorial – Deep Sky Image Processing in Photoshop

Galaxy Season Target – The Leo Triplet of Galaxies

My Complete Deep Sky Astrophotography Equipment Setup

Beginner Astrophotography Telescopes – My Top Picks


Astrophotography Tutorials –

Gradient Xterminator – Photoshop Plugin

Astronomy Tools Action Set – Pro Digital Software

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Deep Sky Image Processing in Photoshop

Well, this is it.  In this deep sky image processing tutorial, I’ll be combining all of the data I was able to collect on the Orion Nebula this winter.  As we transition into Spring, a new array of deep-sky imaging targets will present themselves.  The winter astrophotography targets in the Orion constellation will have to wait another year to get photographed.

The camera used for this image was a Canon EOS Rebel T3i (600D), an excellent choice for beginners looking to dive into deep sky astrophotography.

Deep Sky Image Processing

Processing Walkthrough – Orion Nebula with a DSLR

Canon DSLR for astrophotography

The total amount of detail I was able to capture on M42 this winter was 3 Hours and 8 minutes of color RGB data.  I will be incorporating 2 hours and 40 minutes of Ha data into the final image using the HaRGB processing technique.  In this post, I’ll show you exactly how I process my image of the Orion Nebula using Adobe Photoshop.  I’ll start with the Autosave.tif file produced by DSS.

Some of the images used in my final photo were shot during the AstroBackyard YouTube video: Let’s Photograph the Orion Nebula.


The screenshot below shows the results of registering and stacking 4 nights worth of imaging from my backyard.  This winter has been plagued with numerous cloudy nights, so I had to capture photons here and there, under varying sky conditions.

Yes, it is very white!  That’s light pollution for you.


Orion Nebula stacked .TIF file in DeepSkyStacker

The photo sets from each imaging session were loaded into the group tabs of DeepSkyStacker.  My modified Canon T3i camera was set to ISO 800 for each imaging session, but I bumped the exposure time up to 3.5 minutes for the fourth and final set.

Using the group tabs in DSS

  • Dec 22, 2016 – 23 frames – 180″ @ ISO 800
  • Feb 2, 2017 – 24 frames – 180″ @ ISO 800
  • Feb 3, 2017 – 10 frames – 180″ @ ISO 800
  • Feb 27, 2017 – 11 frames – 210″ @ ISO 800

Image sets 1-3 were stacked using darks, bias and flat calibration/support frames. The final and fourth set did not use flat frames as I was not able to shoot them the morning after the imaging session.

I do not make any adjustments to the stacked image in DeepSkyStacker.  I bring the 32-bit Autosave.tif file into Adobe Photoshop for all post-processing.

Processing in Adobe Photoshop

I use two Photoshop Plugins in this tutorial, Astronomy Tools Action Set, and Gradient Xterminator.  See all of the astrophotography software I use here.

Cropping/Rotating the file in Photoshop

The first thing I like to do is to rotate and crop the image.  A temporary levels adjustment was made to get a better look at the edges of the frame.  As you can see, my frames rotated and shifted slightly between the imaging sessions.  This creates an unusable sky at the edges of the image, so I will crop the image to about 85%.  In the future, I plan to incorporate a plate-solving software such as AstroTortilla to help line up my images over multiple nights.

deep sky image processing

Rotating and cropping the image in Photoshop

To save some of the outer regions around the nebula, I will have to repair some of the outer background sky using the healing brush, and the content-aware fill tool in Photoshop.  Ideally, you would want to keep as much of your original frame as possible.  Once I have cropped the image, I will adjust the black point of the image.

Levels Adjustment / Setting Blackpoint

As you can see in the image below, the histogram shows that the majority of the image data is contained in the mid-level tones.  I will move the slider to the left of the histogram over until it touches the information contained within the image.  This will darken the background sky and increase the contrast of the original image.

Levels adjustment

the first levels adjustment creates much more contrast in the image

The slider to the right of the data was moved inwards as well.  It’s important that you do not clip the data and lose any pixel information.  You may notice that the core of the Orion Nebula is completely white and “blown out”, I will correct this issue later on.

Before setting the initial black-point, I will give the image a semi-aggressive curve stretch to reveal more of the outer nebulosity.  This will also discern where the nebula ends and the background sky begins. Before Photoshop will let us make this adjustment, we will need to convert the image from a 32-bit file to a 16-bit file.

Image > Mode > 16 Bits/Channel

An HDR Toning window will open up.  Avoid choosing the tempting default preset of Local Adaptation, and instead, select Exposure and Gamma from the Method selection area. Leave the default exposure and gamma settings.  As this tutorial moves on, we will be creating our own HDR (High Dynamic Range) version of the Orion Nebula using very specific actions and settings.

At this point, you can adjust the levels once more, as there is likely empty space to the left of the data in the histogram again.  You may also choose to create a copy of your original layer, or create a new adjustment layer to work from.  Having snapshots of your image at each stage of the processing workflow will help you go back and fine-tune your edits.  Personally, I like to use a mixture of new layer copies using the History feature of Adobe Photoshop.

Here is what my initial curve stretch looks like:

curves adjustment in Photoshop


The curves stretch I applied brought forward the fainter details of the outer nebulosity.

Here is a little trick I like to use: With the curves window open, hold down CTRL, and click an area of the nebula you want to bring forward.  This will plot a point on the histogram you can pull from to stretch that particular tonal range.  You can also plot an additional point of a neutral area of background sky, and know that you are pulling data forward from only the nebula itself, and not the space around it.

Levels Once the curve stretch has been applied there are two ways to set the black point of the image.  The Set Gray Point eyedropper in the levels window is great for a quick overall adjustment.  Although some astrophotographers will argue that this method results in a loss of overall range of data.   You can also manually set the color of your background sky by plotting a Color Sampler eye dropper in a neutral area of space.

Using the Info window, adjust the left-hand slider on each RGB level until the values are balanced.  A background sky with Red/Green/Blue values of about 30/30/30 is a good starting point.

Creating a star mask

If you don’t want to risk the chance of brightening the stars in your image and blowing them out, try using a layer mask to protect them from growing in size and intensity.  The art of stretching the deep-sky object, but not the stars is a constant challenge when processing astrophotography images.

You can create this mask by using the Color Range tool.  Select > Color Range.

Select Color RangeThen, use the eyedropper to select a medium-sized star within the frame.  Adjusting the Fuzziness slider will affect how much of the color range (and stars) will be selected.

You will have to experiment with the fuzziness slider to select your intended amount of stars.  In my example, I used a value of 140.  After the stars have been selected, I suggest softening the selection for a more natural blend in the mask.  To do this:

Select > Modify > Expand (2 Pixels)

Select > Modify > Feather (3 Pixels)

Again, these values will vary based on your image scale. If you are shooting wide field through a Canon T3i or similar model, these settings should work well.

Like many tasks in Photoshop, there are numerous ways to accomplish a layer mask adjustment.  For this step, I prefer to invert the selection of stars (Select > Inverse) and make my curve adjustment to all areas of the image except the star mask I created.

Here is what my image of the Orion Nebula looks like at this stage:

Image Processing - Orion Nebula

I cropped the image in a little more and used Gradient Xterminator around the edges of the DSO to balance the background sky.  Again, the core is still blown out at this stage.  I will add 2 additional stacks of 15 and 30-second images of the bright core to reveal the full range of detail in the Orion Nebula.

Astronomy Tools Action Set

At this stage of my image processing workflow, I will use my first action from Noel Carboni’s action set.   The action is called Local Contrast Enhancement.

This action does a great job at sharpening details and increasing the contrast of the deep-sky object.  It is wise to create a new layer with this action applied, so you can toggle the effect on and off.  For my image, I am going to apply a layer with this action at 75% opacity.  I have also created a mask on this layer so that it does not affect the areas of space where I do not want to increase the contrast.

Directly after this action, I prefer to run Enhance DSO and Reduce Stars.  This action can takes up to a minute or more to complete, depending on your image and the computer you are using.  Again, a new layer using this action is recommended, as this action can dramatically change the look of your image.

Here is a before/after look at my image after running Local Contrast Enhancement and Enhance DSO and Reduce Stars:

Photoshop actions before - after

Before and After applying actions in Photoshop

To make a new adjustment layer with all previous actions and adjustments made, use the keyboard shortcut: CTRL + ALT + SHIFT + N + E.  This is a very helpful technique to use as your continue to add adjustment layers to your image.

Applying the “Tamed Core” Layer

At this stage, I will apply a pre-processed stack of shorter exposures to the image.  To capture these images I shot a series of 15-second and 30-second exposures with the goal of collecting detail in the brightest areas of the Orion Nebula.  A good indicator of this dynamic range in values is the ability to discern the individual stars in the Trapezium.

The short exposures were stacked in DeepSkyStacker using dark, bias and flat frames just as the primary image was.

Orion Nebula Core ExposureThese layers were processed in the exact same fashion as the primary image.  This means that similar adjustments were made to the levels, curves, and actions – but in an isolated area.

Blending the two images will be a lot easier if they have been pre-processed in the same manner.  Some may argue that combining the core should have taken place much earlier in the process.  However, this timing of this workflow works best for my personal taste.  With so many opinions about how to properly process a deep sky image, I prefer to lean towards the workflow that I enjoy most.  This way, I can enjoy the hobby for years to come.

Here’s where it gets fun

Select the image of the detailed core, and paste it onto your original image as a new layer.  Rather than using a traditional mask method, I like to use a feathered eraser brush at an opacity of 15%.  This allows me to subtly remove the unwanted data on the top layer (the core), one brush stroke at a time.

When I need to see the faint details of the edges of the core layer, I simply create a 100% white layer and place it as the layer below.  The amount of brightness of the core is a matter of taste.  This aspect of the image has varying points of view as to how an HDR Orion Nebula is “supposed to look”.

I personally think that the Orion Nebula should have a bright core!  With the right amount of blending it is possible to show the full range of detail and keep the core as the brightest area of the image.  Flattening core to a lower brightness than the outer nebulosity can give the nebula a plastic look.

Blending the core

Layering in the core can take a long time if you are particular about the overall look of your image.  I used several copies of both stacks of shorter exposures to gradually work the new core into my existing image.

Final Processing Steps

With the full dynamic range captured in the image (depending on who you ask), I can now go ahead and make my final image processing steps to further increase the color and detail of the image.

Color sampler toolAt this point, I like to double check the levels of color in the background sky.  Using the Color Sampler Tool in 2 areas of the background sky indicates that the image is rather well balanced at the moment.

Increase Vibrance and Saturation

To increase the saturation of the Nebula without bringing noise and unwanted color from the background sky, I’ll use the Select Color Range tool again.  This time, use the eyedropper to select the color from the nebula you wish to intensify.  I choose the mid-level pink areas of Orion.

You may also want to run some actions on your image such as Increase Star Color, and Make Stars Smaller.  As always, apply these actions to a new layer so that you can control the amount of the adjustment using the opacity slider.  I will often use both of these actions, in small amounts.

Adding a layer of H-Alpha

This is where the image really starts to “pop”.  I shot over 2 hours worth of data through a 12nm Astronomik clip filter with my Canon T3i.  I will combine this data with the RGB image we just processed using the HaRGB processing technique outlined in this tutorial:

Deep Sky Image Processing in HaRGB – Tutorial

Orion nebula in Ha

The Orion Nebula in Ha

The image above is 32 X 5-minute subs @ ISO 1600

If you are interested learning how to shoot H-Alpha with your DSLR camera, read my post on how a DSLR Ha Filter can improve your astrophotography.

Without explaining every detail in the HaRGB tutorial I linked above, the premise is basically to add the Ha as a luminosity layer at about 75% over your original color image.

Because the data in the core of the H-Alpha version of Orion was blown out, it is important to note that I removed this area of the Ha luminosity layer, so that I did not lose any detail in the final composite image.  By turning the Ha layer off and on, you can determine which areas of the nebula are being improved, and which areas are losing detail and/or color.  I prefer to create another layer mask using the Ha layer, leaving only the key improvement areas at the full 75% opacity.

Below is my final image of the Orion Nebula using the processing methods outlined above:

Orion Nebula - AstroBackyard

Final Image Details:


Mount: Sky-Watcher HEQ5 Pro Synscan
Telescope: Explore Scientific ED102 CF
Imaging Camera: Canon T3i (600D) Modified
Filters: Hutech IDAS LPS, Astronomik 12nm Ha
Flattener/Reducer: William Optics FF III
Guide Scope: Orion Mini 50mm, Starwave 50mm
Guide Camera: Meade DSI, Altair Astro GPCAM2 AR0130


Image Aquisition: BackyardEOS
Autoguiding: PHD2 Guiding
Registering/Stacking: DeepSkyStacker
Image Processing: Adobe Photoshop CC

Exposure Details:

RGB: 3 Hours, 8 Minutes (55 frames)
Ha: 2 Hours, 40 Minutes (32 frames)
Total Integrated Exposure: 5 Hours, 48 Minutes

Photoshop TutorialI am always looking to improve my deep sky image processing techniques.  For a video presentation of these techniques in action, please visit the AstroBackyard YouTube Channel.  If you like to see more of my deep sky astrophotography images, please have a look at the Photo Gallery.

This winter was a memorable one for me.  By sharing my experiences in the backyard on this blog and on YouTube, I was able to connect with fellow backyard astronomers on a deeper level.  There may not have been many clear nights, but the ones that were felt extra special.  Until next time, clear skies!

Deep Sky Image Processing Help:

Settings for DeepSkyStacker

Video Tutorial: Deep Sky Image Processing in Photoshop

Astrophotography Image Processing Video (YouTube)



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Manual Stacking in Photoshop for Reduced Noise

|Tutorials|4 Comments

Even without a tracking mount, your astrophotography images can benefit from manual stacking in Photoshop. This method involves aligning exposures and combining them into a master composite.  It can make a big impact on your astrophotos by reducing noise and improving the signal-to-noise ratio.

The images used in the example were captured using a camera lens in place of a telescope. A wide-angle lens can be a tremendous way to photograph a large area of the night sky at once, rather than zooming in on a deep sky object.

manual stacking in Photoshop

This night sky photo contains 11 exposures stacked manually in Photoshop

This technique requires no darks frames, no stacking software, and no tracking mount.

The 2 software applications used in this tutorial are Adobe Bridge and Adobe Photoshop. (Lightroom will also work) The main idea is to reduce noise by layering single exposures gradually, effectively canceling out much of the noise from a single frame.  The key is to gradually reduce the opacity of each layer until you reach the top of the image set.

Basic Astrophotography Camera Settings and Tips

Manual stacking is easy with Adobe Photoshop

Let’s say you have taken a 30-second exposure of the starry night sky with your camera on a tripod.  By taking 10-12 shots of the same scene, your final composite version will have much less noise, a smoother background, and more detail.

Watch the video tutorial below:

In my example, the camera happened to be sitting on top of a telescope on a German equatorial mount.  Don’t confuse this fact into thinking this method does not work without a tracking mount.  30-second exposures at wide focal lengths do not contain much star-trailing and are perfect candidates for this treatment.

The reason this technique is referred to as “manual stacking” is that the user layers each exposure manually, rather than loading the frames into Deep Sky Stacker.  The simplicity and effectiveness of this technique is something all astrophotography enthusiasts can benefit from.

Manual Stacking Example

If you are interested in the full explanation of this process, follow the link below.

Astrophotography Tutorial – Align and stack exposures in Photoshop

Capture longer exposures

A small tracking camera mount such as the iOptron SkyTracker Pro allows you to shoot longer exposures than you can on a stationary tripod. The SkyTracker compensates for the rotation of the Earth, meaning that objects in space stay put as your camera collects light.
This is a useful piece of astrophotography gear if you plan on photographing the Milky Way. The following images uses 60 x 2-minute exposures at ISO 1600. The individual images were stacked using DeepSkyStacker, but similar results could be produced using the manual stacking process.
The Milky Way

What’s New?

My deep-sky imaging has been put on hold as it has been cloudy for nearly 3 weeks straight. This weather is sure to get any backyard astrophotographer down. However, my passion for imaging couldn’t be stronger as I have recently added some new astrophotography equipment to my arsenal.  This time, it was my primary imaging camera that needed replacement.

New Camera: Canon Rebel T3i (600D)

After much consideration, I have decided to finally upgrade my primary imaging camera to a Canon Rebel T3i.  If you follow AstroBackyard on Facebook, you may have heard that this DSLR was professionally modified for astrophotography by removing the IR cut filter.  The Canon 600D features an 18MP CMOS sensor capable of producing images 5184 x 3456 pixels in size.  This is a huge leap from the 12MP 450D sensor I was using.

Modified Canon T3i for astrophotographyPowering the camera for a full night of imaging requires more than a single battery charge.  I purchased an AC adapter to plug the camera into an electrical outlet for unlimited power.  I never had this function with my previous imaging camera, and fumbled around with batteries for far too long.  I also sprung for a remote shutter release cable with a built-in intervalometer.  The great news is that this model is compatible with my Canon Xsi as well.

The AC Adapter for the Canon T3i is available on Amazon

Canon t3i AC adapter


I am really excited to start using this camera for deep-sky imaging.  Although tests show that the thermal noise level is comparable with the 450D, the Canon T3i’s increased resolution means larger astrophotos with enhanced detail. Also, the flip-out LCD screen will come in handy when focusing using live view.  This camera was modified by Astro Mod Canada.

Drone Footage?

Did you notice the aerial footage in the latest AstroBackyard video on YouTube?  That video was shot at a friend’s house using a DJI Phantom 4 in his backyard. I absolutely love drone footage and hope to get one of my own in the near future.  There are infrequent situations where that type of footage makes sense for an astrophotography video, but I’ll find a way to work them in!

I’ve also been working away trying to improve the resources on this website.  The photo gallery, equipment, and tutorial sections have seen a number of changes this month.  Thank you to everyone who has taken the time to comment on my blog posts, I really appreciate the kind words.  For the latest information and photos, please follow AstroBackyard on Facebook.

Latest Image Re-Process: The Eagle Nebula

DSLR astrophotography

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Forgotten Light Frames

|Nebulae|0 Comments

While digging though some old folders on Adobe Bridge, I stumbled across some unprocessed, 300 second light frames of the Flaming Star Nebula from November 2013!  When you are desperate to get out and image a new target, this is like hitting gold.  

I was originally looking for my raw files of the Pacman Nebula, which I feel is in desperate need a new process. (Those stars look pretty rough)  I found a folder labeled “Flaming Star – 5 Min Lights”.  I never processed this image!  The Flaming Star Nebula is a colorful collection of glowing gas and dust lit up by the bright star AE Aurigae. 

The tough part about this process will be the limited exposure time.  1 hour of data is really not ideal for a quality astrophotography image.  I find that out the hard way below:

IC 405 – The Flaming Star Nebula

IC 405 - Flaming Star Nebula

Photo Details

Photographed on: November 29, 2013

Telescope: Explore Scientific ED80 with WO Flat III 0.8x FR/FF
Guiding: Meade DSI Pro II and PHD Guiding
Guide Scope: Orion Mini 50mm
Camera: Canon EOS 450D (Stock)
ISO: 1600
Exposure: 1 hour (12 x 300s)
Processing Software: Deep Sky Stacker, Photoshop CC
Support Files: 15 darks

Guided with PHD Guiding
Stacked in Deep Sky Stacker
Processed in Adobe Photoshop CC

This image was acquired using Canon EOS Utilities, and not BackyardEOS as I use now.  This was photo was also shot before I modified my Canon 450D for astrophotography.

Now you might be thinking “how could you spend hours imaging a nebula and forget to process it?”  It’s simple – life is busy!  I likely had a busy week following the imaging session and began I new session before I even looked at the precious data collected on that cold November night.  I don’t see any dark frames to support the image.  

This may have been another reason I held off.  I bet that I wanted to take 5-minute darks of the same temperature before stacking but never got around to it.  This could be a problem.

But first, let’s get this cleared up

This is budget Astrophotography. Most of my gear was purchased used from online forums and astronomy classifieds.  The total value of the equipment used to photograph this nebula was purchased for under $3,000.  It’s not top-of-the line gear by any stretch of the imagination.  My astrophotography image processing skills were self-taught.  I am no scientist, that’s for sure. Just like you, I have a strong desire to capture beautiful images of the night sky.  I always appreciate constructive criticism and enjoy helping others learn through my mistakes.

Stacking without Dark Frames?

First of all, I’ll have to use dark frames from a different night to stack with the Flaming Star light frames.  This means that it is very important to match the temperature of my light frames from that night of imaging.

I have done a poor job of creating a master dark library, so finding matching dark’s may be tough.  I usually try to record the temperature of my dark frames in the file folder, for this very situation.  There are external software applications available that can help create a dark frame library, such as Dark Library.  

I remember using this years ago, but their website appears to be down right now.  I will use the 5-minute dark frames from my Pacman Nebula image taken earlier that month, labeled 4 degrees.

Another option is to just stack the light frames without any darks. I’ll try both and compare the two.

Here is the version stacked with no dark frames:

Deep Sky Stacker with No Darks

Here is the version using dark frames from a previous night:

Deep Sky Stacker with Darks

As you can see, stacking with the dark frames produced a better result.  Even though the temperature of dark frames did not match perfectly, the dark frames removed some of the dead pixels and noise from the image.  Notice the red streak of dead pixels on the “no-darks” version.  All of these imperfections would become intensified after processing!  

I performed a few basic edits to the examples above to have a better look at the differences. (Levels, Gradient Xterminator, and Curves)  Now that we have registered and stacked our 1 hour’s worth of data, let’s start stretching the data in Photoshop.

How to take proper Dark Frames for Deep Sky Stacker

The answer to this and more in the FAQ section

Processing the Image in Photoshop

If you have followed any of my astrophotography tutorials on my website, or video tutorials on YouTube, you already know the basics of my processing workflow.  This process has evolved over the years as I learn new tricks.  However, processing the Flaming Star Nebula was particularly tough because of the limited exposure time on the subject.  

Add in the fact that this nebula is quite faint, with many bright stars surrounding it, and you’ve got an astrophotography challenge for even the most experienced astrophotographer.

Quick Astrophotography Tip

Try to frame your deep-sky object in an interesting way.  Include nearby star clusters, nebulae, or galaxies.  For inspiration, search for your target on APOD, and see how the professionals have framed the object.  This may spark your creativity to photograph an existing target in a different way.

HLVG – Green Noise Remover

The entire image had a noticeable green cast over it, perhaps because of the extreme amount of noise, or the miss-matched dark frames.  I ran Deep Sky Colors HLVG on medium, which helped a lot.  HLVG was created by Rogelio Bernal Andreo of RBA Premium Astrophotography. 

It is a chromatic noise reduction tool that attempts to remove green noise and the green casts this noise may cause in your astrophotography image.  It is based on PixInsight’s SCNR Average Neutral algorithm.  If you don’t already have this useful filter for Photoshop, I highly recommend it, it’s free!  You can download the plugin here:

Hasta La Vista, Green!

HLVG Filter for astrophotography

Results and Thoughts

I must admit, this post became a bit of a nightmare.  I began to document my processing steps one by one, taking screenshots of progress along the way.  I wanted to provide a detailed tutorial of how I turned this forgotten data into a masterpiece, despite having no associated dark frames, and only an hour’s worth of exposure time.  As I experimented using different methods of noise reduction, and various orders of operations, I became very discouraged with my final image results.  

I spent hours taking different roads with all of my trusted astrophotography tools at my disposal, and the results continued to be unimpressive.  By adjusting the curves enough to show any substantial detail on the nebula, I introduced a frightening amount of noise into the background space.  No amount of noise reduction could remove it, without turning the entire image into a blurry mess.

I just couldn’t bring myself to post a tutorial with the end result turning out as it did.  So I scrapped the idea and settled for a forgettable image of the Flaming Star Nebula.  Surely this gorgeous nebula that spans 5 light-years across deserves more than that.

Astrophotography Processing Tutorial

My unused processing tutorial screenshots

At the end of the day:

No amount of processing can make up for lack of exposure time!

I guess you could say I was doomed from the start.  I am not going to spend any more time on this image until I am able to capture at least another 2 hours of data on it.  I hope you can learn from my experiences in astrophotography, in both victories and failures.  But I guess that’s why you’re here 🙂  Please follow AstroBackyard on Facebook for the latest updates.

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Selective Processing for More Detail

Staying Inside – Image Processing

The unseasonably cold weather and precipitation we have experienced here in Southern Ontario have given me the perfect opportunity to go through my old astrophotography images and reprocess the data.  I have been advancing my image-processing skills by studying current astronomy images taken by the pros.

Being a creative professional myself, I have always understood and appreciated the power of inspiration. I am always interested in new image-processing techniques, Photoshop tutorials and new software that can enhance my work.  Through selective processing, I have been able to squeeze out the most amount of detail from my astro images.

Western Veil Nebula

The Western Veil Nebula – I reduced the stars to show more contrast in the nebula

My latest take on The Swan Nebula is my favorite version yet. Through selective processing, I was able to tame the background stars, while intensifying the gorgeous pinks and reds in the nebula itself.  

I also recently reprocessed my wide-field image of the Western Veil Nebula, with a focus on reducing star size, and overall image contrast and color. The “witch’s broom nebula” is a tough process, especially if you have to deal with a severe gradient behind all of those stars. After assessing the gradient in Photoshop, (mostly due to heavy light-pollution) I can easily even out the sky background using the Gradient Xterminator plugin.

I am quite pleased at my latest results of the Eagle Nebula as well. I went through my astrophotography folders from the past 4 years (like I said, it’s been cloudy!)  and found a set of almost 2 hours of frames on M16 that I had not previously used!  

I combined all of the data together from May 2012, and May 2013 in DeepSkyStacker to create an image with over 3 hours of exposure time.  I decided to keep the extremely wide-field view captured by my 80mm telescope, rather than cropping the photo around the nebula.

This image really benefited from the selective processing technique. By reducing the stars on a separate layer, I was able to keep all of the detail found in the nebula.

Eagle Nebula - 80mm Telescope

Wide field image of the Eagle Nebula with my 80mm telescope

Image Processing Techniques

One of the processing techniques I have been implementing into my photos is to process different elements of the image separately. By this, I mean to process the background, the stars and the nebulosity on their own.  

I am able to do this by selecting each element of the image and stretching the data without affecting the other areas. For example, I can boost the vibrance and saturation of the nebula or galaxy without adding additional noise to the background of space and stars.

As I have stated many times, I prefer to tame the stars in the image to be as small as possible. Normally, I would run the “make stars smaller” action to the entire image in Photoshop.

This actually starts to diminish the precious detail in your deep-sky object that you worked so hard to capture! Many other actions that are intended to correct issues with the background space and stars can take away from your subject as well.

You can also manually Remove the Stars Completely from your image using photoshop.

Swan Nebula - 8 Inch telescope

My latest version of the Swan Nebula

Selective Processing

There are several ways to accomplish the selective processing technique to your astronomy photos.  You can create multiple adjustment layers of your image in Photoshop, and apply the various actions to each element of the image on a separate layer.

I use the Select and Mask tool to refine my selections before applying effects. This ensures that each new adjustment layer is blended naturally into the final image.

 Once you have applied your desired settings applied to each layer, you can use layer masks to combine all aspects of the photograph into one.  This means you will likely have layers for:

  • The Background Space – With a balanced black-point set

  • The Background Stars – Small, sharp and with lots of accurate colour

  • The Brighter Stars – Soft, or with Diffraction Spikes and Color

  • The Deep-Sky Object – Full of luminance, color and detail

  • The Core or Brightest Area of the DSO – reduced to show detail, not blown out

Selective Processing - Astrophotography

Processing the nebulosity separately from the background stars in Photoshop

You can also process the selected elements of your images as separate documents.  Sometime I prefer to do this to really focus on achieving the best possible result for my focus area, without the temptation to poke around at another feature.  

Once you have processed each version of the image with your focus area maximized, you can then combine the images using layer masks.  The blending and layer masking is definitely the most delicate stage of the process.  You can really make a mess of an image by failing to inspect all areas of your image before flattening.

I find it helpful to use a reference image of your deep-sky target. This is the best way to make sure you have not overstretched your image data, and that your colors and details are an accurate portrayal of that particular deep sky wonder. I often look for inspiration on APOD!  

To stay connected with me and my latest astrophotography images, please follow my Facebook Page.  I hope you are all excited about the wonderful deep-sky targets that will be gracing our night sky the coming months, I sure am!


Astrophotography for Beginners – The Basics

How to choose an Astrophotography Camera – My Advice

Top 5 Telescopes for Beginners – My Advice

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Astrophotography Video Tutorial

|Blog Updates|2 Comments

Astrophotography Video Tutorial

Astrophotography Video Tutorial

In my first ever astrophotography video tutorial, I take a crack at the Rosette Nebula using data collected in February 2014. I have plans of shooting a video about light frame acquisition in the future, but this one is about what happens after you have already captured your data.  This astrophotography video tutorial may be useful to anyone who has questions about the stacking process, and processing the created .TIF file in Adobe Photoshop.

I must admit, I learned a lot about how I could improve upon these videos in the future during the process.  Putting together an online tutorial video using a particular piece of software is harder than it looks!  Nevertheless, I believe new astro-imagers will find some useful information in my video.

My astrophotography processing techniques

In the video, I discuss the importance of organizing and inspecting your raw image files before you dive-in to Deep Sky Stacker.  The application I find most useful for this stage is Adobe Bridge.  I subscribe to the Adobe Creative Suite that includes all of the Adobe applications, so using Bridge as my default image viewer was a no-brainer.  I know that Adobe Lightroom is another popular choice for this purpose as well. Alternative methods for viewing RAW image files on your PC are Faststone Image Viewer, Canon EOS Utilities and installing the proper codec on your particular version of Windows to preview the files.  I have used Faststone Image Viewer and Canon EOS Utilities, but I have not tried the Windows Codec option.

Video Summary

Using DeepSkyStacker, I register and stack over 2 hours worth of 3.5 minute light frames I captured of the Rosette Nebula with my Canon Xsi and ED80 Telescope. As always, dark frames are subtracted from the final image to produce a final image with a higher signal-to-noise ratio.  I then locate and open the 32 bit Autosave.tif file into Adobe Photoshop CC for further processing using helpful astrophotography plugins including Gradient Xterminator and the Astronomy Tools Action Set.  The order of the actions I make when processing an astrophoto from the RAW image files to the final result are as follows:

  1.  Stack and register light and dark frames in DSS
  2.  Open Autosave.tif file in Adobe Photoshop
  3.  Slight Image Crop to remove stacking artifacts
  4.  Removal of gradient and vignetting via Gradient Xterminator
  5.  Levels Adjustment
  6.  Convert to 16-bit/channel image
  7.  Curves Adjustment
  8.  Astronomy Tools Action > Local Contrast Enhancement
  9.  Astronomy Tools Action > Enhance DSO and Reduce Stars
  10.  Astronomy Tools Action > Increase Star Colour
  11.  Astronomy Tools Action > Make Stars Smaller
  12.  Balance neutral background sky colour
  13.  Increase Saturation
  14.  Final Curves Tweaks

The Learning Curve

Up until this point, I’ve been the student, not the teacher.  I want to show beginners how I process my astrophotography images, but my presentation skills leave much to be desired. I have always been an artist at heart, so my methods may seem unorganized and random to the general public.  I am more likely to “trust my eyes” rather than a set of numbers and graphs, although I recognize their value.  I feel that through the process of teaching others how to capture and edit photographs of the night sky, I will gain a deeper appreciation and knowledge of the hobby for myself.  Thank you to everyone who has subscribed to my YouTube channel so far.  I am just getting started.


AstroBackyard on YouTube

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