Brighten

Questions and postings pertaining to the usage of ImageMagick regardless of the interface. This includes the command-line utilities, as well as the C and C++ APIs. Usage questions are like "How do I use ImageMagick to create drop shadows?".
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magick
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Post by magick » 2006-04-15T08:00:52-07:00

The cost of the image brightness algorithm increases linearly with the area of the image:
  • convert logo: -resize 100% logo.mpc
    time convert logo.mpc -modulate 50% null:
    0.060u 0.032s 0:00.09 100.0% 0+0k 0+0io 1pf+0w
    convert logo: -resize 200% logo.mpc
    time convert logo.mpc -modulate 50% null:
    0.212u 0.060s 0:00.26 103.8% 0+0k 0+0io 0pf+0w
    convert logo: -resize 400% logo.mpc
    time convert logo.mpc -modulate 50% null:
    0.816u 0.152s 0:00.98 97.9% 0+0k 0+0io 0pf+0w
    convert logo: -resize 800% logo.mpc
    time convert logo.mpc -modulate 50% null:
    3.300u 0.480s 0:03.95 95.6% 0+0k 0+0io 0pf+0w
    convert logo: -resize 1600% logo.mpc
    time convert logo.mpc -modulate 50% null:
    12.604u 2.336s 0:27.17 54.9% 0+0k 0+0io 49pf+0w

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magick
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Post by magick » 2006-04-15T18:55:14-07:00

We're using ImageMagick 6.2.6-8 and we tried these commands under Windows XP:
  • convert sp001.jpg -modulate 105% bright.jpg
    convert bright.jpg -modulate 105% bright.jpg
    convert bright.jpg -modulate 105% bright.jpg
    convert bright.jpg -modulate 105% bright.jpg
    ...
and each command completed in under a second.

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magick
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Post by magick » 2006-04-16T12:00:22-07:00

Certainly testing the current release would be helpful since we have shown it works fine (no hanging when modulating).

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