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by Centigonal 4829 days ago
The the image consists of a checkerboard-style pattern of pixels. The "dark" pixels form the apple image, while the "light" ones show the pear. The answer to the SO question suggests that the gamma correction information (which is used by Chrome and FF, but not by older IE) makes the image darker, blacking out the apple and revealing the pear. Without gamma correction, the apple is visible, and the pear becomes a light-colored ghost.

edit: I put together the pieces! yay! :D
2 comments
corysama 4829 days ago
Hmm... I'm quite familiar with gamma correction. For those who are not, I recently did an "Explain Like I'm Five" http://www.reddit.com/r/explainlikeimfive/comments/1aeuyb/el...

But, my understanding is that for an image displayed 1-1 pixel-to-screen there is no intermediate math going on. So, there shouldn't be any opportunity for non-gamma-correct calculations to screw up the output.

Here's a nice example of non-gamma-correct browsers producing incorrect results after scaling an image: http://filmicgames.com/archives/354 also http://www.4p8.com/eric.brasseur/gamma.html But, in the SO question there is no scaling. So, I'm still confused about the difference in visual results between different applications directly displaying the image...

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Steuard 4829 days ago
Even when there's no scaling involved, gamma information embedded in an image can certainly be meaningful. Among other things, they can be used to correct for the fact that different OS's or devices can assume different default gamma factors. Without gamma correction, an image edited on a Mac might look different when viewed on a PC. If the image can tell the browser what gamma factor it was designed for, that problem can be avoided.
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corysama 4829 days ago
That's exactly what I was forgetting. Different systems assume different display gammas such as 1.8, 2.2 or sRGB (a mix of 1.0 and 2.4). Thanks!
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Glyptodon 4829 days ago
On my machine I can see both of them, but neither is particularly distinct, as though two 40% transparency images were stacked.

So obviously my various image viewers aren't reading the gamma correction to show the pear, however I'm more curious why I don't see the apple correctly if the image has been intended to show the apple without gamma/color correction?

My monitor is color calibrated, so shouldn't I just see the apple and not the pear?

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