[Bug 346474] Re: ImageMagick interprets PGM header incorrectly

[Launchpad Bug Tracker]

[Expired for imagemagick (Ubuntu) because there has been no activity for
60 days.]

** Changed in: imagemagick (Ubuntu)
       Status: Incomplete => Expired

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https://bugs.launchpad.net/bugs/346474

Title:
  ImageMagick interprets PGM header incorrectly

Status in imagemagick package in Ubuntu:
  Expired

Bug description:
  Binary package hint: imagemagick

  Ubuntu 8.10
  imagemagick 7:6.3.7.9.dfsg1-2ubuntu3

  When reading a PGM-P5 (binary) image with a maxval of 256, the
  'convert' and 'display' utility, and likely the rest, will interpret
  each pixel as one byte, when it should interpret each pixel as two
  bytes since 256 is more than 255. This causes vertical stripes and
  other nastiness in the image. If maxval is set to 257, everything
  works as it should.

  Apparently you can only submit one attachment in this bugtracker so users have to host their own files. Download example images from:
  http://natrox.ath.cx/imagemagick/lena-255.pgm
  http://natrox.ath.cx/imagemagick/lena-256.pgm
  http://natrox.ath.cx/imagemagick/lena-257.pgm

  Display with imagemagick:
  $ display -sample 400% lena-255.pgm
  $ display -sample 400% lena-256.pgm
  $ display -sample 400% lena-257.pgm

  255 and 257 works, 256 breaks.

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