Even at high quality setting, the U/V quantizer step is limited
to 4 which can lead to banding on gradient.
This option allows to selectively apply some randomness to
potentially flattened-out U/V blocks and attenuate the banding.
This option is off by default in 'dwebp', but set to -dither 50
by default in 'vwebp'.
Note: depending on the number of blocks selectively dithered,
we can have up to a 10% slow-down in decoding speed it seems.
Change-Id: Icc2446007f33ddacb60b3a80a9e63f2d5ad162de
-> helps debanding (sky, gradients, etc.)
This dithering can only be triggered when using -preset photo
or -pre 2 (as a preprocessing). Everything is unchanged otherwise.
Note that this change is likely to make the perceived PSNR/SSIM drop
since we're altering the input internally.
Change-Id: Id8d4326245d9b828141de162c94ba381b1fa5813
method 1 grouping: [parse + reconstruction] // [filtering + output]
method 2 grouping: [parse] // [reconstruction+filtering + output]
Depending on some heuristics (see VP8ThreadMethod()), we
can pick one of the other when -mt flag (or option.use_threads)
is selected.
Conservatively, we always use method #2 for now until the heuristic
is refined (so, timing should be the same the before this patch)
+ replace 'use_threads' by 'mt_method'
+ define MIN_WIDTH_FOR_THREADS constant
+ fix comment alignment
Change-Id: I11a756dea9070d6e21b1a9481d357a1e8aa0663e
Mostly visible for large images.
Reconstruction+filtering is now done in parallel to bitstream-parsing.
Change-Id: I4cc4483d803b255f4d97a2fcd9158b1c291dd900
Needs more memory but allows for future parallelization.
Noticeably faster on ARM, slightly faster on x86
also: remove dec->filter_row_ unnecessary field
Change-Id: I044a808839b4e000c838a477e3e8688820436d9a
happens surprisingly often at low quality, so we might
as well hard-code a simplified TransformWHT() directly.
Change-Id: Ib7a858ef74e8f334bd59d6512bf5bd3e455c5459
happens when decoding is partial (past Partition0), without error and
interrupted by calling WebPIDelete()
WebPIDelete() needs to call VP8ExitCritical() to free in-flight resources
Change-Id: Id4faef1b92f7edd8c17d642c58860e70dd570506
If 'top' was meant to be NULL, then bottom and top can be
swapped. Logic is simpler.
+ fix compilation in non-FANCY_UPSAMPLING mode
Change-Id: I7c62bbb59454017f072c0945d1ff2d24d89286ff
This speeds up WebP lossless decoding by 20%. In particular, the
photographic images get 35% speedup.
Change-Id: Idb94750342a140ec05df52c07e12be4bba335adc
speeds up those codes that are not part of the main lookup.
This gives a 10 % speedup for a photographic image.
Change-Id: Ief54b0ad77db790a01314402ad351b40ac9a7be4
Specialize and simplify the alpha-decoding case, which is used when:
- no color-cache is use
- all red/blue/alpha values are the same (and hence their Huffman tree has
only 1 symbol. We don't need to consume any bits for reading these).
+ revamped the loop to use size_t and offsets instead of pointers.
~2-3% faster on Unix (gcc) but up to 25% faster lossy+alpha decoding
on Mac (llvm) and ARM.
Change-Id: I43c9688d1e4811cab0ecf0108a5b8f45781083e6
* 0.3.0: (57 commits)
update ChangeLog
Regression fix for alpha channels using color cache:
wicdec: silence a format warning
muxedit: silence some uninitialized warnings
update ChangeLog
update NEWS
bump version to 0.3.1
Revert "add WebPBlendAlpha() function to blend colors against background"
Simplify forward-WHT + SSE2 version
probe input file and quick-check for WebP format.
configure: improve gl/glut library test
update copyright text
configure: remove use of AS_VAR_APPEND
fix EXIF parsing in PNG
add doc precision for WebPPictureCopy() and WebPPictureView()
remove datatype qualifier for vmnv
fix a memory leak in gif2webp
fix two minor memory leaks in webpmux
remove some cruft from swig/libwebp.jar
README: update swig notes
...
Conflicts:
NEWS
examples/gif2webp.c
src/dec/alpha.c
src/dec/idec.c
src/dec/vp8l.c
src/enc/alpha.c
src/enc/vp8l.c
Change-Id: Ib202fad7825a090c3b3a5169acd171369cface47
+ split AllocateInternalBuffers() into two 32b/8b variants instead of
trying to do everything in one function.
Change-Id: I35cac9fcd990a2194c95da4b2a4046ca3a514343
Considering the fact that insert to/lookup from the color cache is always 32
bit, use DecodeImageData() variant in that case.
Conflicts:
src/dec/vp8l.c
Change-Id: I6c665a6cfbd9bd10651c1e82fa54e687cbd54a2b
(cherry picked from commit a37eff47d6)
Considering the fact that insert to/lookup from the color cache is always 32
bit, use DecodeImageData() variant in that case.
Change-Id: I6c665a6cfbd9bd10651c1e82fa54e687cbd54a2b
src\dec\vp8l.c(816) : warning C4244: '=' : conversion from '__int64' to
'int', possible loss of data
src\dec\vp8l.c(817) : warning C4244: '=' : conversion from '__int64' to
'int', possible loss of data
Change-Id: I1d376d5dea909395bff8741aba16e8eed83a6e8f
