Red Hat Bugzilla – Bug 154621
"pnmtopgm" handles transparency incorrectly when working with colormapped PNG
Last modified: 2013-07-02 19:07:01 EDT
Description of problem: "pnmtopgm" handles transparency incorrectly when working with colormapped PNG Version-Release number of selected component (if applicable): netpbm-10.25-2 How reproducible: fails predictably Steps to Reproduce: 1. grab a PNG from the pixmaps directory 2. convert it to PNM 3. reduce the colors below 256 to enable colormap handling 4. use pnmtopng with -transparent option, so for example... pngtopnm /usr/share/pixmaps/gnomemeeting-splash.png | pnmdepth 10 | pnmtopng -trans white > /tmp/test4.png Actual results: white region of picture is not transparent Expected results: white region of picture should be transparent Additional info: 1. Worked fine in FC2. 2. Run that pipeline above about 20 times; it will occasionally seg-fault. 3. If you leave the "pnmdepth 10" step out, then pnmtopng doesn't try to create a colormapped image, and the transparency works correctly. 4. This is my first time reporting a bug, so I hope I don't totally suck.
I tried that with netpbm-10.26.4 and netpbm-10.27 and I see it works now. So upgrading to the latest devel netpbm should solve your problem. (the white colour is transparent in the /tmp/test4.png image) Jindrich