(The sibling comments are good but I want to add this anyway) Wikipedia has a static test image for gamma here https://en.wikipedia.org/wiki/File:Gamma_correct

(The sibling comments are good but I want to add this anyway) Wikipedia has a static test image for gamma here https://en.wikipedia.org/wiki/File:Gamma_correction_test_picture.png https://en.wikipedia.org/wiki/File:Gamma_correction_test_pic... If you look in the green section, you can see the background is a checkerboard of (0, 0, 0) black and (0, 255, 0) green. Because of gamma, this is not equivalent to (0, 127, 0). The 2.6, 2.2, 1.8 sections are supposed to blend with the background if that's the gamma that your image-to-screen pipeline uses. (Including the browser's PNG decoder, the browser's painting and compositing, the desktop's painting and compositing, anything goofy the GPU drivers do, and all the goofy stuff monitors do) Looks like my cheapo 2010 LCD's gamma changes greatly depending on viewing angle. Ugh :S