All the values containing
more than one byte, as written in Portable Network Graphics specification
must use Network Order format, it means that the most significant byte
must come first followed by the less significant. ([Byte more significant]
[Byte less significant] for 2 bytes values or B3 B2 B1 B0 to 4 bytes
values). The more important bit (value 127) from a byte is bit 7 and the
less important (value 1) is bit number 0.