I simply turn off gamma correction, which imo can make the image look flat, dull, washed out, and it kills highlights/shadows. GC can look nice if you take all the required steps as mentioned by other posters above, and set up the materials properly, but imo simply too much work for the results. If you're a photoshop person like me, just tick it off and apply it as needed in PS. Also if you're losing a bit of photorealism due to turning GC off, theres many softening techniques and hdr-toning that will really make your image pop out and realistic. It works for me since my images are 40% poser 60% photoshop. If you don't use photoshop, then IDL will give that realistic look, and most IDL sets i've seen actually require you to turn off GC.