Preprocessing / Optimization / Re compression For Better Compression of Games

[kj911]

Introducing QOI — the Quite OK Image format. It losslessly compresses RGB and RGBA images to a similar size of PNG, while offering a 20x-50x speedup in compression and 3x-4x speedup in decompression. All single-threaded, no SIMD. It's also stupidly simple.

https://phoboslab.org/log/2021/11/qo...ge-compression

Nice preprocessors from visually losslessly recompress PNG files smaller than ~30 to 50% percentage to original ones. (Hint: compress encoded QOI files use CM/LZ* or any algo.)

Compressed PNG files to QOI format, its bigger or smaller than original PNG file and fairly compressibble than orig. PNG files. Decoded PNG files its smaller/bigger than original PNG files. Not bitperfect lossless compression. Visually lossless only.

Example:

Original test.png file: 213 745 bytes
QOI file: 398 930 byte
Decompressed PNG file to QOI file: 336 428 byte
Compressed QOI file with RAR: 96 430 byte (internal size in archive)

Example2:

pg-coral.png 265K
pg-coral.png.balz 266K // balz cannot improve png!
pg-coral.qoi 371K // seems bad? but not if further compressed
pg-coral.qoi.zip 250K // better than PNG!
pg-coral.qoi.balz 222KB // even better! total-code size (Balz + qoi + strip comments&headers) is maybe 500 lines of code.

I think if qoi used my suggestions (tiling+delta), we can get the file much smaller, maybe 200K.

Further tests with XZ:

pg-coral.qoi.xz 182KB

Again, if qoi used tile+delta, maybe we can get the file down to 150KB? (using xz)

Compiled Win XP x86 compatible EXE attached.