On Tue, Apr 15, 2014 at 6:15 AM, anshul <anshul.ffmpeg@gmail.com> wrote:
I am using following command
pnmtopng -alpha=dvbs.0-a.pgm dvbs.0.ppm

It should be "-alpha dvbs.0-a.pgm" instead of "-alpha=dvbs.0-a.pgm"
i.e., replace the "=" with a space in the command line.

I am getting this error.
libpng warning: Invalid color type in IHDR
pnmtopng: fatal libpng error: Invalid IHDR data

The message is confusing because the command was itself confused
by the syntax error.