[RESOLVED] Cannot convert one specific pgm file, others work fine

[mimetus]

I have a bunch of pgm files that have all been processed in the same way, and I'm running a convert script on every file, and at least one file fails to convert.

Even if I run the following:

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convert F0023240.pgm test.pgm

It returns the following:

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convert.im6: negative or zero image size `F0023240.pgm' @ error/pnm.c/ReadPNMImage/416.
convert.im6: no images defined `test.pgm' @ error/convert.c/ConvertImageCommand/3044.

The file in question can be found here:https://www.dropbox.com/s/hkfzwb3i42721 ... 0.pgm?dl=0

I have no idea why this file does not work, i can view the file just fine in gimp and ubuntu image viewer.

I use the following version:

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convert -version
Version: ImageMagick 6.7.7-10 2014-03-06 Q16 http://www.imagemagick.org
Copyright: Copyright (C) 1999-2012 ImageMagick Studio LLC
Features: OpenMP 

Thanks
- Mimetus

[glennrp]

• glenn.rp> od -c F00* | head
  0000000 P 5 \n 8 3 2 7 6 8 \n 2 5 5 \n \n
  0000020 375 376 377 377 376 376 376 375 375 376 377 377 375 376 376 377

(a bit confusing, on screen I see a space between 832 and 768)
File length seems OK, 832 * 768 + 16 = 638992

• glenn.rp> wc F*
  4 5 638992 F0023240.pgm

[mimetus]

Thanks for the reply.

This file have the exact same byte count and works fine with convert https://www.dropbox.com/s/ytx91s777zahd ... 5.pgm?dl=0

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~$ wc -c F0023240.pgm
638992 F0023240.pgm

~$ wc -c F0000015.pgm
638992 F0000015.pgm

~$ convert F0000015.pgm test.pgm

~$ convert F0023240.pgm test.pgm
convert.im6: negative or zero image size `F0023240.pgm' @ error/pnm.c/ReadPNMImage/416.
convert.im6: no images defined `test.pgm' @ error/convert.c/ConvertImageCommand/3044.

[glennrp]

Netpbm (pnmtopng) can read the file. Recent IM6-Q16 and IM7-Q8 both reject it.

[mimetus]

So you suggest convert to png? That could be a workaround of course.
Thanks for your help! Though i guess the bug is still open?

[magick]

Try

• convert 'F0023240.pgm[0]' test.pgm

This file is corrupt. It ends with a 'P' after the image data so ImageMagick thinks there is another image in the file but fails when it can't find any.

[mimetus]

This works! Thanks a lot! Though I don't agree that the file is corrupt, it's structured according to the PGM specification, and other programs read the file just fine.

Thanks for the help!

[magick]

Your PGM has a blank line between the maximum gray value and the image data. The PGM specification says:

• The maximum gray value (Maxval), again in ASCII decimal. Must be less than 65536, and more than zero.
  A single whitespace character (usually a newline).

Suggesting your PGM is corrupt, it has *two* whitespace characters.

[mimetus]

I tried removing the extra whitespace character and you are correct, resulted in convert working again. Thanks allot!

Additionally, I can see that the programs that handled the image before are off by one pixel along the edge, translating it to the next row.