Metadata in PGM file not being preserved

[dchaddock]

Description

When running "convert" on a PGM file with metadata between the magic number and dimension/bitdepth lines, any new line characters are removed. This behaviour started at 7.0.8-x from what I can tell. All prior versions that I have worked with have preserved the new line characters (7.0.7, 6.x).

Head of file before running convert:

$ head -n 6 white.pgm 
P5
# metadata line 1
# metadata line 2
# metadata line 3
100 100
65535

Head of file after running convert:

$ head -n 4 new.pgm 
P5
# metadata line 1 metadata line 2 metadata line 3
100 100
65535

If this isn't a bug, would it be possible to add in a flag of '-preserve-exact-metadata' or something like that?

Steps to Reproduce

1. Create a blank PGM file
   convert -size 100x100 xc:white white.pgm
2. Insert metadata into file
   sed -i -e '/^P5/s/P5/P5\n# metadata line 1\n# metadata line 2\n# metadata line 3/g' white.pgm
3. Run convert (note, I realize that running convert on this image actually doesn't accomplish anything, but, it's the most basic example)
   convert white.pgm new.pgm

System Configuration

• CentOS 7, x64, kernel version, kernel 3.10.0-862.14.4.el7.x86_64
• Behaviour occurs on ImageMagick 7.0.8-16, 7.0.8-14
• No problems with ImageMagick 7.0.7-22, 6.x

[urban-warrior]

Thanks for the problem report. We can reproduce it and will have a patch to fix it in GIT master branch @ https://github.com/ImageMagick/ImageMagick later today. The patch will be available in the beta releases of ImageMagick @ https://www.imagemagick.org/download/beta/ by sometime tomorrow.

[dchaddock]

Great, thanks!

[dchaddock]

This seems to be happening again in Imagemagick 6.7.8-9. I'm not sure when it was reintroduced though.