RE: ... aPNG (Animated PNG)

From: Glenn Randers-Pehrson
>Kato-N wrote:
>> 1. Adding a new chunk for disposal methods to MNG-LC,
>
>Right, that looks easy and simple.  The devil is in the implementation.
>I would at least have two chunks, one that marks the beginning of any
>stream that is going to be needed for dispose-to-previous later on,
>and the actual dispose-to-previous instruction.

GIF has two basic operations combined into one.  They are:

1) SAVE the current frame buffer
2) RESTORE the previously saved frame buffer

The "save" occurs before a frame with "restore to previous" disposal, the
"restore" occurs after the time delay specified for the frame.

If I remember MNG correctly the *only* thing this requires is to make a COPY
of the current abstract image - APNG needs one abstract image (the size of
the logical stream) and *at most* one copy of it.  The copy is only ever
used to replace the current abstract image.

John Bowler <[email protected]>


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