3 ms·
The check-summing in PnG is poorly designed. It uses 2 different checksum on top of each other. The format itself checksum each chunk, but then the pixel data i
by quelsolaar 6y ago
The check-summing in PnG is poorly designed. It uses 2 different checksum on top of each other. The format itself checksum each chunk, but then the pixel data is using zlibs compression header that have a second checksum on top of that, using a different algorithm.
- astrange 6y agoMost everything about PNG is poorly designed. Using a text codec to encode image data doesn't make any sense even if you pre-filter it. A consequence of this is how much larger PNG files get with alpha, even if the alpha channel has no information in it. Lossy codecs with lossless modes tend to be a lot more efficient although may be harder to decode.