Post Production Deep Sky in Adobe Photoshop CC with Astro Panel

In this article I will explain how to perform deep sky workflow or edit deep sky images in Adobe Photoshop CC

If you are interested in the milky way workflow please visit this page and if you want to buy “Astro Panel 3.0” click here. The workflow for the post production of the deep sky images is very similar to the Milky Way and differs only in the use of some groups of commands such as “Star Tools” and “False Flat”.

If we have stacked our images in Fusion, The first step is to reset the colors with the command “RC – Reset colors Astrophotography”.

In astrophotography images, it can happen that there is a green cast. To decrease it,  we use the command “RG – Remove Green color”.

Using the “RG – Remove Green color” command, the background is duplicated and we can adjust the opacity to achieve the result we want. We merge the levels after adjusting the green dominant. Our next task is to analyze the histogram at the top right of our image. This is necessary when we switch to the other group of commands to understand which function to use. We are talking about the “Streching Image” group, which brings out the hidden signal in the image. In this case, we use the “SD” button, as our image is underexposed. Use the “SB” button only if your image is overexposed. We recommend using the “SD” command several times only if your photo is still underexposed after the first click.

The image has now become a lot of brighter and we were able to pull out the signal of the nebula that was almost absent before. Our task now will be to clean the image from this bright gradient with the “False Flat” commands. First command to use is “1” which generates the artificial flat that we should subtract from our starting image. Then we will click on “25” or “50” or “75” based on the percentage of gradient we want to remove from the image. If the result does not satisfy us we can go back with the dedicated key down and repeat the two operations.

Based on the power of your computer, the command will take from 30 seconds to a few minutes to process the artificial flat. For a better job, I recommend using the clone stamp tool to hide the nebulae and other objects in the deep sky in order to obscure them from the next subtraction.

Once you mask the areas of the image you want to protect, click on the desired percentage. In this example, I executed the “50” command to subtract 50% of the gradient.

At this point, we extract even more signal and give more depth to the nebula with the “Enhance” commands. As explained earlier, we click on “EL – Enhance Luminance” and “EN – Enhance Nebulosity” to extract the luminance and nebulosity of the image. From now on, we work on the nebula to extract the detail and the dominant red color. Another command that comes to our aid is “DS – Dynamic Stretch”.

The next step will be to work on the fine detail and try to reduce the diameter of the stars. For this, we have the commands of the group “Sharpness” such as “PB-Precision Boost”, “HP – High Pass Filter” or “DE – Deconvulation”. Step-by-step let’s start with the “PB-Precision Boost” command to work on micro-details with a white brush. Then click on “HP – High Pass Filter” and “DE – Deconvulation”. With the command “DE – Deconvulation” we have the possibility to adjust the opacity of the level to find the right compromise with advanced sharpness. This technique is used often in astrophotography and is useful to reduce the shake of astronomical images. See the image below page to see the effect of combining these commands.

We can reduce the brightness with tonal values or the command “RH – Remove Haze” by adjusting the opacity of the layer.

 

Let’s return to work on the sharpness and use again the commands of the group “Sharpness”, precisely “PB – Precision Boost” and “DE – Deconvulation”. The “PB – Precision Boost” command duplicates the base level and, with the aid of a white brush, we highlight the faint filaments of the nebula. On the other hand, with the command “DE – Deconvulation” we can give our photo a general sharpness and, simultaneously, reduce blur. You can also use the other controls in the group and use different combinations. The most important thing is not to exaggerate the sharpness.

After that, let’s work on the stars using the commands of the “Star Tools” group of functions.

In the image above, I wanted to reduce the stars and accentuate the nebulosity.  To this end, I clicked the “SS – Select Stars” command and the “Curves” adjustment button. With the adjustment tool on the image (the “little hand”), I lower the curve to gradually turn off the stars, without exaggerating. In just two clicks, I performed a very complex job with the only help of Astro Panel.

To achieve this, you can also use the “SF – Star Filter” function, even though the result is better and far more accurate with the technique just described.

Heavy graphic processing can generate some digital and chromatic noise. To correct this, I used the “NS – Noise Reduction Soft” command. When using this, the base level is duplicated so to adjust the opacity of the effect. If there is  a lot of digital and chromatic noise to correct, use the “NH – Noise Reduction Hard” command. If there are artifacts in the background, use the “BC – Background Correction” command, which corrects this. In this case too, the base level is duplicated to regulate its opacity.

Once we have corrected the “defects” of graphic processing, we move on to correcting the color. In Astro Panel, there are many functions for color management, but color masks allow us to get the most out of our images. Indeed, in our case we use the color mask “R – Red Mask Selection”, which automatically selects the red color that is present in the nebula. After your selection, you can liven up the color using the “Hue / Saturation” or “Curve” settings. In the image above, I increased the saturation and the luminosity of the red color.

Apply this workflow to any color or luminosity mask. You can also mask out with a black brush the areas of the image that are not affected by the current modifications.

Once we have finished working with colors, we can introduce contrast in the image with the “Curve” adjustment or with the “CI – Constrast Image” command. This command duplicates the base level so to adjust the opacity of the effect. In both cases, the result achieved will be identical.

We can then cut out the portions of the image that are  either affected by light pollution or that we do not find interesting. However, this is just a piece of advice.

Finally, the command “OR – Orton Effect” is used here to give a soft effect to the image and its opacity is set to 15-20%.

What is described in these tutorials is only a small glimpse into the potential of Astro Panel. You can use the tutorials as guidelines for you to try to find the right combination of features and the right workflow for you.

 

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