From: OFFICE XV [mailto:
jack@...]
>Is anyone aware of a PNG decoder that is available in VHDL or RTL code to
>run on an fpga?
I'm probably way out of date on FPGA capabilities, but unless there is an
efficient way of implementing about 256kbyte of memory the answer is
probably no. PNG uses deflate (LZ77) compression, this is where the main
memory requirement comes from. It also has to buffer at least one row of
the output pixels in the original (decompressed form).
If there is a satisfactory FPGA implementation of deflate (Internet RFC
1951), or maybe even if there is a suitable LZ77 implementation, then it
might be possible. However memory requirements seem large to me - current
FGPA implementations of gzip deflate exist; "google: VHDL LZ77 IEEEXplore"
(a 2007 paper), but I don't know how a window size they support.
The paper is:
FPGA-Based Lossless Data Compression using Huffman and LZ77 Algorithms
Rigler, S. Bishop, W. Kennings, A.
Univ. of Waterloo, Waterloo;
If you *can* do the decompression then the actual PNG decoding part is much
easier, so long as you can avoid interlaced images.
John Bowler <
jbowler@...>
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