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kornelski / mediancut-posterizer

Lossy PNG compressor for RGBA PNGs. Has two modes: lossy averaging filter (blurizer) that denoises the image and optimal posterization using Median Cut quantization to reduce number of unique colors in the image with minimal visual distortion

Home Page:https://pngmini.com

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Update version to match ImageAlpha

joeyhoer opened this issue · comments

commented

The version of posterizer provided in ImageAlpha is different from posterize as it exists in this repo. This becomes evident when running the following:

$ posterize -v 64 test.png test.png
MSE=20.288 (Q=43, 64 levels)
$ wc -c test.png
210715 test.png

$ /Applications/ImageAlpha.app/Contents/MacOS/posterizer -v 64 test.png test.png 
MSE=17.192 (Q=50, 64 levels)
$ wc -c test.png
137719 test.png
commented

It's the same source, but difference is from build config. You'll get the same result when you build it from ImageAlpha's Xcode project. It's probably difference between using Cocoa vs libpng for reading.

commented

Trying to build from ImageAlpha fails with an error:

Undefined symbols for architecture x86_64:
  "_optimizeForAverageFilter", referenced from:
      _main in posterize.o

Trying to build from the command line using USE_COCOA=1 make fails because pam.h isn't linked. After including the files from libimagequant, I get a second error: error: unknown type name 'LIQ_PRIVATE'.

Any thoughts on what's missing?

commented

I've added the missing file and set up posterizer as a submodule (git clone --recursive; or git submoodule init)

commented

It also requires ImageOptim to be checked out in sibling directory to ImageAlpha :)

commented

Front-page mentions switch -b, but Posterizer 1.6 says invalid option, why?