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edec2b9baa
"TPGD" is short for "Typical Prediction for Generic Direct coding",
and the "ON" bit turns it on. In this mode, before decoding a line,
we decode a single bit first that controls if the current line is
just a copy of the previous line. If so, the line's pixels aren't
encoded, the decoder just copies the previous line.
I created this by running
jbig2 -i Tests/LibGfx/test-inputs/bmp/bitmap -f bmp \
-o bitmap -F jb2 -ini tpgdon.ini
where tpgdon.ini contained:
-Gen -Seg 1
-Gen -Param -TpGDon 1
See previous commits in this directory for details on the `jbig2` tool.
Sadly, the TPGDON writing path in `jbig2` wasn't implemented yet,
so I had to add this. See the PR that added this commit for my
local diff to `jbig2`.
I'm somewhat confident that my change to `jbig2` (and hence the
image added in this commit) is correct because:
1. `jbig2` succeeds in converting this file to a bmp file,
while it failed without my patch (the decoding codepath in
`jbig2` does have TPGDON support)
2. Other pdf viewers display the output of
`Meta/jbig2_to_pdf.py -o foo.pdf path/to/bitmap-tpgdon.jbig2 399 400`
the same way we do
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||
|---|---|---|
| .. | ||
| bmp | ||
| dds | ||
| icc | ||
| ico | ||
| ilbm | ||
| jbig2 | ||
| jpg | ||
| jxl | ||
| png | ||
| pnm | ||
| tga | ||
| tiff | ||
| tvg | ||
| webp | ||
| woff | ||
| woff2 | ||
| download-animation.gif | ||
| loop_forever.avif | ||
| TestFont.font | ||
