Chances are you have seen at least one deep space image from the Hubble Telescope.  This pictures are amazing to be sure, but these amazing photos are actually made quite easily using Photoshop, a custom program called FITS Liberator, and three different grayscale images.  The official instructions from the Hubble website are available here, but I will briefly explain them to you.

The three grayscale images are all identical photos except that the wavelength of each photo varies.  Below are the three photos of the “Pillars of Creation”, part of the Eagle Nebula, that I used:

After converting the files using FITS Liberator, the photos are then imported into Photoshop and manually all inserted into the same file, each as a separate layer.  After sorting the files by wavelength, highest to lowest (top-down), each layer received a “color action”, with the first being red, the second green, and the third blue.  These can be applied manually, but I downloaded a pre-made one here.  After manually adjusting the default settings for each action, the combined (not merged) photo now looks like photos you have probably seen.

The Pillars of Creation photo I was able to create in Photoshop:

The Photo NASA created:

The Pillars of Creation are just a small segment of a giant stellar cloud, or nebula, called the Eagle Nebula.  The Nebula is located close to 7,000 light-years from Earth, in the constellation Serpens.  This is an actual star forming nebula, unlike the Crab Nebula, where the term nebula is actually misused.  The Eagle Nebula actually contains known active star-forming regions, including the Pillars of Creation.

Here is a photo of the Pillars of Creation overlayed on the whole nebula, with other notable landmarks overlayed as well.