convert: coders/png.c:7013: WriteOnePNGImage: Assertion `(unsigned long) packet_index < number_colors' failed.

[IMq]

Dear all,

I am trying to reduce the bit-depth of a PNG image to 8-bit using the following command:
convert input.png -colors 256 png8:output.png

The error I am receiving is the following:
convert: coders/png.c:7013: WriteOnePNGImage: Assertion `(unsigned long) packet_index < number_colors' failed.

I am using the following version/ platform/ API:
Version: ImageMagick 6.5.4-7 2014-01-30 Q16 OpenMP http://www.imagemagick.org
Platform: Linux
API: Bash Shell

Anybody knows why I it is not working?

Vera

PS: I don't see the option to upload the image to help testing

[dlemstra]

Can you upgrade to the latest version and see if you can reproduce the problem? Your version is ancient...