FITS Tutorial Intro Page
Up FITS Tutorial Intro Page MegaPixels and JPEGs Bits and Stretching

“FITS or Flexible Image Transport System a digital file format used to store, transmit, and manipulate scientific and other images.”

These series of tutorials is to specifically help users to process FITS formatted files in Photoshop through “FITS Liberator”. This is *not* a Photoshop how-to or tutorial. I’m going to *assume* you have a basic understanding of Photoshop, but I will also explain some rudimentary steps so that we're all on the same page. I will delve into some theory that should help you to understand why we need FITS formatted files when dealing with astrophotography and why using a program like Maxim or Photoshop is absolutely mandatory. The video sections show PhotoShop CS2. You really need Photoshop CS or higher. Photoshop version 7 *can*, but that version doesn't deal with 32 bit files. You have to do some tweaks to get it to work. (I will not cover Photoshop 7 here.)

To download FITS Liberator, go to the ESA FITS Liberator download page.

Before embarking on how to process FITS formatted files in Photoshop, we need to go over some theory and basics. This is the theory stuff that you may or may not want to go through. If you do, you will be much better equipped to understand why Photoshop does some of the things it does. If not, or if you have a good understanding of Photoshop layers and blend modes, go on to the video sections on using FITS Liberator.

Photoshop is an image manipulation tool. In some cases it will allow us to go and change things without affecting the original image. Other times it will change the image itself. You need to be aware of what we can haphazardly change and where we need to be careful.


One of Photoshop’s biggest strengths is its ability to deal with layers and blending modes. Layers are just that- layers are whole or partial images that can be manipulated, and can appear in parts or a whole on top of the layers underneath it. There are also interesting ways to have those layers interact with the layers below using something called “Blend Modes”. Normally, when you create a new layer, its blend mode is “Normal” (pun alert).  One of the blend modes is called “Color”. This will transfer the color of a pixel to the pixel under it, without changing the brightness value. (This is a great way to colorize old Black and White images!) As we go through this, you will see that this little tidbit is critical to the development of a FITS image.

Another Photoshop strength is something called an “Adjustment Layer”. This is a layer that you can have certain adjustments and it will either influence all layers under it or just the layer directly below it. For instance, a lot of people have used “Levels” at one point or another. But did you know you can apply Levels as an adjustment layer so that you can go back and tweak the picture without having really changed the original picture? A lot more people have used and become frustrated with “Curves”, but take heart - you will find your images look a LOT better using Curves. Both of these adjustment layers will be used in the development of FITS files.

For more on why JPEG is a very nice format to see pictures, and why we need to use the FITS format to work on astrophotography pictures, go to the Megapixels and JPEG section, or go back to the title page.