How to use PNG's IDAT chunk?

Question

I\'m trying to understand how data are stored into IDAT chunk. I\'m writing a little PHP class and I can retrieve most of chunks information but what I get for IDAT doesn\'t mat

Answer 1

00000000 ffffff00 ffffff00 0000xxxx
black    white    white    black

That's what I can tell (which is correct) ... but you are missing 2 bytes at the end.