possible bugs in PNG8 IM 6.5.3-2 -any updates?

[fmw42]

IM 6.5.3-2 Q16 Mac OSX Tiger.

(Two possible bugs)

First potential bug. I am not getting what I believe should be the correct behavior when convert a Class: DirectClass and Type: GrayscaleMatte PNG (with alpha channel) to PNG8 (expecting Class Pseudoclass and Type: GrayscaleMatte) so as to get a smaller filesize.

Here is the image I got from http://studio.imagemagick.org/pipermail ... 22567.html

Original


I removed the alpha channel to see what was there and also extracted the alpha channel:

Image without alpha:
convert jobs_original.png -alpha off jobs_original_aoff.png


Image alpha channel:
convert jobs_original.png -alpha extract jobs_original_alpha.png


So looks fine to me.

Now when I do:
convert jobs_original.png PNG8:jobs_original_png8.png


It is not what I expected

But when I make it gif, it looks like what I expected:
convert jobs_original.png jobs_original.gif


And if I do:
convert jobs_original.png GIF:- | convert - jobs_original_gif_png.png


The above also looks right and is of Class Pseudoclass and Type: GrayscaleMatte (so smaller filesize)




Second potential bug. When I do

convert jobs_original.png GIF:- | convert - PNG8:jobs_original_gif_png8.png

I now get an error message:
coders/png.c:6990: failed assertion `(unsigned long) packet_index < number_colors'
Abort trap

[fmw42]

Is there any further information about these two bug reports? Have they been validated? Are they bugs or am I misunderstanding something?

Thanks.

Fred

[magick]

We forwarded this bug to glennrp. He is the current maintainer of the PNG module. Feel free to ping him about the problem. If you need an address, send a PM.