Wednesday, November 12, 2008

Quick PNG Raster Compression Comparison

After reading this blog entry about using PNGNQ which I have also been using,I thought it would interesting to do a quick and dirty comparison

All images where created just using the default command line options,

i.e. util.exe filename.png

Imagery was sourced from http://www.unearthedoutdoors.net/global_data/true_marble/download






















MapGuide PNG32 2.0.2  138.174 Kb NQ8 pngnq 0.5   56.055 Kb
NQ8+pngcrush 1.6.10   49.762 Kb NQ8+OptiPNG 0.6.1   49.420 Kb MapGuide PNG8 2.0.2   38.728 Kb

It turns out that MapGuide comes out on top in when configured for PNG8 :)

Now if only the GDAL FDO provider was stable...

2 comments:

klokan.cz said...

Hi, can you please point me to the algorithms MapGuide is using to optimize PNG8 to this form?
Will it correctly convert true alpha channels (not only two/state) as well?

Klokan Petr Přidal said...

I mean images like this: http://trac.osgeo.org/gdal/attachment/ticket/1939/1244-nq8.png?format=raw