

Ngnq is a tool for quantizing PNG images using neuquant algorithm. - MikeCapone
http://pngnq.sourceforge.net/

======
sirn
Few benchmarks using Cmd+4'd of my working Firefox window.

Tested with:

    
    
      pngnq -n 256 image.png
      optipng -o7 image.png
      advpng -z4 image.png
      pngout image.png
    

Results:

    
    
      312822  test-firefox.png
      181394  test-firefox-advpng.png
      199005  test-firefox-optipng.png
      235635  test-firefox-pngout.png
      181394  test-firefox-full.png
      
       79793  test-firefox-nq8.png
       74917  test-firefox-nq8-advpng.png
       79683  test-firefox-nq8-optipng.png
       76017  test-firefox-nq8-pngout.png
       74917  test-firefox-nq8-full.png
    

Samples:

    
    
       Original   http://gridth.s3.amazonaws.com/test-firefox.png
       Quantized  http://gridth.s3.amazonaws.com/test-firefox-nq8.png
    

The result file size is impressive, but the image quality is noticeably worse.
I'm not sure if I want to use color quantization with PNG though. After all,
if I want a lossy compression, I'd use JPEG.

~~~
For_Iconoclasm
This is exactly what I don't understand about the existence of this program. I
don't know much about compression algorithms, but this is definitely lossy
compression. I don't know why somebody would want to use it on their lossless
PNGs when JPG already exists.

~~~
chipsy
PNG8 allows you to use alpha in palettized form. Images you want to use in a
"composite" context(icons, buttons, sprites, etc.) really need alpha to look
great, but you don't usually need the full color gamut for them either.

------
chipsy
This is a great tool, I used it to palettize spritesheets for my last game.
Caveat: it sometimes palettized the 0-alpha values to 1, resulting in a very
faint box around affected images.

