I have been trying to open a .png file in a hex editor, and keep changing stuff around, trying to achieve a data-moshing like effect. According to wikipedia, the image itself is inside the IDAT chunk, so i have been messing with that one most. The problem is that no matter what i change, no matter how small the change is, even when it's inside a chunk, the image just doesn't render anymore. Is the PNG format that hard to break?
I seem to have solved my question. After every PNG chunk, there are 4 bytes of CRC-32 Checksum. I also need to calculate that, or the chunk will be invalidated.