Reduces size used for oramap files from 2,774,405 bytes to 2,614,332 bytes in total. The smaller files also improve loading times as the zlib decoder has less bytes to schlep through.
The PNG decoder shipped with OpenRA only supports a bit depth of 8 for images with a palette, so must must ensure that other depths (1,2 or 4) are not used.
zopfilpng is used for compression with the following command line:
'zopflipng.exe --keepcolortype -y -m image.png image.png'
The keepcolortype flag ensures the bit depth is not changed.
The oramap files were updated by:
- Saving as a folder, unpacking the data in loose files.
- Compressing the png files using the command above.
- Saving back as an oramap, except instead of regenerating the map preview on save we save the existing version on disk.
