Invisible <voi### [at] devnull> wrote:
> If you generate a PNG image without any fancy filtering, then you don't 
> need any extra memory except for the DEFLATE compressor. But usually PNG 
> files use filtering to increase compression. (I don't know, but I'd 
> *hope* libpng provides a way to control this...) If filtering, you may 
> need the previous row of pixels [only].

  I think PNG has options to filter with the previous row, the previous
column, or both. I assume that if you choose to filter with the previous
column only, you don't need to store the previous row of pixels in memory
at all. (I don't know if libpng optimizes in this way, but at least in
theory I think it could be possible to implement png compression like that.)

-- 
                                                          - Warp

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