Search found 8 matches

by pornel
2015-07-19T04:56:08-07:00
Forum: Developers
Topic: Use pngquant (libimagequant) for quantization to palette
Replies: 13
Views: 26501

Re: Use pngquant (libimagequant) for quantization to palette

The filter wouldn't have to know anything about the PNG tRNS chunk. ImageMagick's PNG encoder will write an indexed PNG with a tRNS chunk when it receives an image with 256 or fewer colors, including the background color. This is the limitation I would like to avoid. As far as I understand to make ...
by pornel
2015-07-18T10:57:04-07:00
Forum: Developers
Topic: Use pngquant (libimagequant) for quantization to palette
Replies: 13
Views: 26501

Re: Use pngquant (libimagequant) for quantization to palette

No, I did not mean command line at all, but a C API. In the beginning of the tread I've been told to use the C filter API to integrate pngquant, but I suspect that's been a misunderstanding, because from what I've seen in the documentation and examples the filters API is technically incapable of pro...
by pornel
2015-07-16T14:31:37-07:00
Forum: Developers
Topic: Use pngquant (libimagequant) for quantization to palette
Replies: 13
Views: 26501

Re: Use pngquant (libimagequant) for quantization to palette

Could you tell me which function call can I use to write tRNS chunk?

The docs point to analyze.c example, but that's read-only filter, so I don't know how to write PNG chunks.

http://www.imagemagick.org/source/analyze.c
by pornel
2015-04-23T16:04:30-07:00
Forum: Developers
Topic: Use pngquant (libimagequant) for quantization to palette
Replies: 13
Views: 26501

Re: Use pngquant (libimagequant) for quantization to palette

Bump.

Filters cannot do this. As far as I can tell it's not possible for a filter to emit a tRNS chunk.

Would you consider just integrating pngquant directly?
by pornel
2013-11-10T10:04:00-07:00
Forum: Developers
Topic: Use pngquant (libimagequant) for quantization to palette
Replies: 13
Views: 26501

Re: Use pngquant (libimagequant) for quantization to palette

bump.

Unfortunately I wasn't able to get filters to compile, but maybe somebody else would like to give it a try?
by pornel
2013-08-19T07:56:17-07:00
Forum: Developers
Topic: MagickFilterKit - convert does not try to load filters
Replies: 3
Views: 5898

Re: MagickFilterKit - convert does not try to load filters

Thanks for checking it out. Unfortunately that doesn't work on my OS X machine. Do I need to configure ImageMagick in some special way to support loadable filters on OS X? My build does not seem to be using external filters at all, and instead only using ones that were compiled in: sudo rm /usr/loca...
by pornel
2013-08-09T11:43:59-07:00
Forum: Developers
Topic: MagickFilterKit - convert does not try to load filters
Replies: 3
Views: 5898

MagickFilterKit - convert does not try to load filters

Is ImageMagick supposed to dynamically load filters? I'm trying to develop a filter, but can't even get it to run. convert ~/Desktop/test1.png -process analyze -verbose info: runs the stock analyze filter, even if I modify and rebuild+reinstall the example. If I rename the filter to "quantize" follo...
by pornel
2013-05-03T15:55:46-07:00
Forum: Developers
Topic: Use pngquant (libimagequant) for quantization to palette
Replies: 13
Views: 26501

Use pngquant (libimagequant) for quantization to palette

I've refactored pngquant into a library (libimagequant) that can be embedded in other software (BSD-like license). I'd like to propose incorporating this library into ImageMagick. Quantization algorithm currently used by ImageMagick posterizes images unnecessarily, doesn't support alpha transparency...