I’m sure everyone out there followed a similar curve of skill when it comes to astrophotography. For me, I started out with a massive growth in the quality of my images for the first few months as I absorbed information, then I hit the limits of my gear and my growth collapsed. From then on every time I got new gear I took a big leap in image quality until I started seeing diminishing returns. I’m at the point where my gear no longer automatically makes my images massively better and most of the quality is coming from my own skill. You can see this in my gallery, where my Leo Triplet image was taken with the same gear as my M51 image. M51 looks significantly better even though it was shot with the exact same setup under similar sky conditions. This is where the importance of processing comes in.

Black Point

In my opinion, literally the most important step people need to take when editing, getting the black point right. This is the level of black you set your background sky to be in an image. Most people just assume that it’s best to set the RGB value to 0,0,0 and be done. This is bad every single time. The night sky isn’t a perfect computer generated black, it’s a dark shade of gray. You want the black point to contrast your object but not look unnaturally or digitally black. It’s very easy to set the black point in basically all editing programs, but don’t get carried away and just drag the black point right into the histogram curve.

Saturation

Along with black point, beginners often make the mistake of just pushing saturation as far as they can. While I understand that art is subjective, I have never seen an image with overblown saturation that I’d consider good. There’s a few reasons for this, but as you drag saturation up you also increase the brightness of noise pixels which obviously isn’t good. You also make the image look hugely unnatural and fake. I’m not saying don’t have saturation, but take it easy and do increases of 10/20% at a time, switching back and forth to see before and after. Rushing through processing will only make your images worse.

Noise

Noise is the primary enemy of astrophotography. There is, as expected, tons of noise when taking images of extremely faint objects trillions of miles from Earth. Dealing with this can be difficult, but doable if you know what you’re doing.

First, try to decrease noise using dithering. Dithering is basically using guiding to shift your imaging by a couple of pixels in order to shift the noise. This keeps the noise very deep in the image data and helps to not bring it to the foreground. Cooled cameras will further decrease this, which also means you’ll have the least noise when it’s cold outside since your sensor will be kept cool.

The second method you can try is the camera raw filters that come built into Photoshop. There you can quickly smooth out color and monochrome noise and in my experience it works fairly well. The main issue is it is global and definitely softens your image. I generally won’t go over a value of 25 for it because it just smooths things out too much. Topaz AI denoiser is also very popular but it isn’t designed for astrophotography and I’ve found that from time to time it will leave weird artifacts.

Thirdly, and by far the most complex, is by using Jon Rista’s denoising technique done in Pixinsight. This is by a long way, the best denoising method I’ve found so far. It leaves you with a sharp image that has very little noise if done well. It takes some time to get it right and requires a fair bit of technical knowledge regarding Pixinsight, but the tutorial makes it pretty easy and I’ve included the link to part 1 of it below. I highly recommend you take a look as it is also very informative on how noise works. This method involved a lot of masking which protects your object from the noise reduction, meaning you don’t get a softening effect much at all.

Masking

Speaking of masking, it’s one of the most important things you’ll ever learn for image processing. Masking is the difference between a beginner image and an experienced astrophotographer’s image. None of the images in my gallery were processed without masking as I have largely thrown out images that old. Essentially what you’re doing when you mask is you’re selectively hiding and revealing different areas of the image in order to only edit certain parts. This is used for color and saturation adjustments, noise reduction, brightness edits and so much more. Stay tuned because I am currently working on a full beginner to expert level course on astrophotography that will go way more in depth and provide actual downloadable Pixinsight workflows that I use. In the meantime, look up masking for noise reduction (or see Jon Rista link above) and color masks. In the future you can use complex masks to reveal very faint details in images, but they are very complicated to do and even I am still learning the more complex masks.

Astronomy Tools Action Set

This is more specific to Photoshop, but it has been invaluable to my editing when I used Photoshop for the whole process. It is $21.95 and includes preset actions you can quickly run to improve your images including noise reduction, curves, false flat creation, mono image color combination etc. It makes editing far faster and your images will definitely look better because of it. Others online like Trevor Jones have been talking about it for years and for good reason.

There isn’t much in the way of tutorials on what everything does, so maybe I’ll make one in the future, but it really isn’t too hard to wrap your head around it.

Stretching

If you’re currently an astrophotographer, how many times have you seen beginners or even people with expensive gear stretching their images well beyond where they should be to get more detail out of them? I see it all the time and all it does is result in an unnatural looking image that has a ton of noise. The problem is as you stretch your image you’re also stretching the noise. As you continue to stretch you’re dragging that noise to the surface of your image making it look grainy. This may look good on a small phone screen but anything bigger and it falls apart. Stretch your image until it’s about 20% away from the left of the histogram and then only do selective edits with masking to go any further as a general rule of thumb. This is really personal preference but it is the rule I stick to and I think it’s worked out well.

Final Thoughts

I put a lot in this one page so my best advice is to take everything slow and really soak up as much information as you can. The biggest takeaway you should have from all of this though is that you want your images to be balanced. You don’t want them to be too saturated or too bright or have a perfectly dark black point. Astrophotography is both a science and an art and in that way it can be really difficult to make articles on how to do it. As an art there is no way to do it since everything is subjective, but as a science you want to keep the integrity of the art by making your images true to life and natural. You aren’t doing space any justice by making it look like a nuclear color bomb went off with the saturation slider. Finding the right balance is something everyone is constantly working towards and it’s something that I don’t think I’ve found yet for my own work, but with work and experience it comes and that’s how you’ll develop your own style.