[dspeyer]

I also had trouble calling either "more even". The first one has greater division at the darker end, and the second at the lighter, but they about balance out.

The extreme for me was figure 12. A and B are so similar I can't see the line between them, but C (the "corrected" square) is a completely different shade.

I'm viewing on a data projector. That's probably the reason. Still, it makes me skeptical that there's anything display-agnostic you can do for gamma.

[ZenPsycho]

The major point the article makes is not about any particular display. It is about image processing algorithms, such as color blending, anti-aliasing, resizing, etc.

All these algorithms assume they are performing math on linear scale measurements of physical light. However, most image data is not encoded as linear scale samples of light intensity. Instead they are gamma encoded.

What the article gets slightly wrong though is that images are not gamma encoded to deal with the non linear response to intensity of the human eye. Instead, it's to deal with the non linear response of CRT displays to linear amounts of voltage, as produced by camera sensors. The gamma encoding adjusts the image data so that a display will correctly produce linear scales of light intensity to match the physical light measured from a scene.

You are rightly skeptical that Gamma Encoding can't really deal with the broad variety of different displays. However, it is still the case that most images are gamma encoded with roughly gamma 2.2, and that all image processing algorithms on the other hand assume gamma 1.0, and misbehave on data that is gamma 2.2

It is, of course still the case that by chance, human visual response is roughly the inverse of gamma 2.2. But bringing this up while trying to make a point about performing operations on linear gamma data is somewhat distracting.

[hunter2_]

If the resolution you're sending into the projector matches the native/optimal/recommended resolution of the projector (in at least the long dimension, and it will letterbox the other dimension), and you set the digital keystone to neutral/zero, you will achieve a 1:1 pixel mapping that is required to be in compliance with the author's statement that "These examples will only work if your [browser|projector|etc]* doesn’t do any rescaling on the images below."

* Author only said browser, but actually everything in the chain matters. If you're not at a 1:1 pixel mapping you're resampling, and resampling breaks the checkerboard example. Digital keystone (but not optical keystone with tilting lenses) included.

[johnnovak]

More even = an even gradation from black to white.