Format specification for Activated Pseudo Format (APF)
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Purpose:
Activated Pseudo Format is a simple-as-possible format created for
demostrative encoders and decoders.

Format:
APF images are all 32bit alpha/red/green/blue images of the following
form:

[Header]
  Signature       ASCII string "APF"
  Width           Big-endian 32bit integer image pixel width
  Height          Big-endian 32bit integer image pixel height
[Data]
  Pixel data      Right to left, top to bottom pixel data in
                  big-endian integers with 8 bits per channel,
                  ordered alpha, red, green then blue.

