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How does Auto-Adjust in Images work ?

example : alt text
(source: iphoneography.com)

Glorfindel
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mr.bio
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  • Can you give a specific example? – Chris O Jan 25 '10 at 01:46
  • @Chris O : I edited.. and posted an example :) – mr.bio Jan 25 '10 at 01:50
  • Looks like Histogram Stretch, rather Equalization, you are maximizing the contrast on all channels equally. – Chris O Jan 25 '10 at 01:51
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    What do you mean by auto-adjust? Auto-adjusting of the color? – Hamish Grubijan Jan 25 '10 at 01:54
  • @Hamish Grubijan : YES ! – mr.bio Jan 25 '10 at 01:59
  • Naive answer - compute average brightness of the image, take in the desired average brightness, and then adjust each pixel. For computer-vision purposes I would compute the average brightness as ab = sum ((r^2+g^2+b^2)/(255^2*3)), and I would adjust (using db = desired brightness) as: r* = r * db / ab, g* = g * db / ab, b* = b * db / ab for every (r,g,b) in the image. However, human perception differs from the way web cam works, so there might be a better formula. – Hamish Grubijan Jan 25 '10 at 02:21

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