this avoids local-minima that look bad, even if the distortion
looks low (e.g. gradients, sky,...). Mostly visible in the q=50-80 range.
Output size is mostly unchanged.
Change-Id: I425b600ec45420db409911367cda375870bc2c63
* raise U/V quantization bias to more neutral values
* also raise the non-zero AC bias for Y1/Y2 matrices
(we need all the precision we can for U/V leves, which are often empty)
This will increase quality in the higher range (q >= 90) mostly.
Files size is exacted to raise a little (5-7%). and SSIM accordingly of course.
Change-Id: I8a9ffdb6d8fb6dadb959e3fd392e66dc5aaed64e
kLevelsFromDelta[sharpness][delta] is an inverse look-up table
that tells the minimum filtering strength needed to trigger the
filtering of a step with amplitude 'delta'. We use this table
in various situations:
a) when computing the initial (/global) filtering
strength for each segment. We look at the quantization
step and deduce the proper filtering strength needed
to result this quantization noise (talking the -f option
into account).
b) during intra16 calculation, when a block ends up
very empty (only DC coeffs are non-zero, all ACs have
vanished). We'll rely on the in-loop filtering to
restore the smoothness (if the source was gradient-like
smooth. That's why we look at the distortion too before
triggering the filtering).
Step b) goes _in addition_ to a), potentially raising
the filtering strength if blockiness is likely.
Change-Id: Icaeca93ef21da195b079e6587a44d9edfc8e9efa
-> 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
"src\enc\frame.c(88) : warning C4244: '=' : conversion from 'const double' to 'float', possible loss of data"
Change-Id: I143cb0bb6b69e1b8befe9b4f24b71adbc28095c2
The convergence algo is noticeably faster and more accurate.
Try it with: 'cwebp -size xxxxx -pass 8 ...' or 'cwebp -psnr 39 -pass 8 ...'
for instance
Allow full-looping with TokenBuffer case, and make the non-TokenBuffer
case match too.
In case Partition0 is likely to overflow, retry encoding with harder
limits on max_i4_header_bits_.
This CL should make -partition_limit option somewhat useless,
since the fix made automatically (albeit in a non-optimal way yet).
Change-Id: I46fde3564188b13b89d4cb69f847a5f24b8c735b
* fix VP8FixedCostsI4ÆÅ table
(the constant cost '211' was erronenously included)
* use the rd-score for '211' correctly (calling SetRDScore() for good)
* count partition0 bits separately during rd-opt
No meaningful difference in rd-curve.
Change-Id: I6c49a150cf28928d9a92c32fff097600d7145ca4
When -mt is used, the analysis pass will be split in two
and each halves performed in parallel. This gives a 5%-9% speed-up.
This was a good occasion to revamp the iterator and analysis-loop
code. As a result, the default (non-mt) behaviour is a tad (~1%) faster.
Change-Id: Id0828c2ebe2e968db8ca227da80af591d6a4055f
-pass 2 can be useful sometimes. More passes usually don't help more.
This change is a step toward being able to re-code the whole picture
with varying parameter (when token buffer is used).
Change-Id: Ia2538e2069a53c080e2ad248c18a1e04623a9304
* move yuv_in_/out_* scratch buffers to iterator
* add y_top_/uv_top_ shortcuts in iterator
That's ~3k of stack size instead of heap.
But it allows having several iterators work in parallel.
Change-Id: I6a437c0f2ef1e5d398c1d6a2fd4974fa0869f0c1
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
Also created variant VP8LPrefixEncodeBits that returns the
code & extra_bits only.
There's no impact on compression density and compression speed.
Change-Id: I2cafdd3438ac9270cd72ad9d57b383cdddfdfa4c
Speed up HashChainFindCopy by optimizing on number of calls to
FindMatchLength method.
This change speeds up the lossless & lossy (Alpha) encoding by 20%
without loss of compression density.
At method=3, lossy (Alpha) compression speed (and density) remains
unchanged, as at that settings, the costly Backward Refs method is not
called
Change-Id: Ia1797148e9e4ee2787011837fa248afbae2242cb
Disable costly 'BackwardReferencesTraceBackwards' for encoding Alpha plane.
Increase the threshold for triggering 'BackwardReferencesTraceBackwards' to
quality 25 and above. Also lower the Alpha quality (at method 3) to be
lesser than this threshold (25).
Change-Id: Ic29fb2e6943472c564223df9fe099b19ccda0f31
This speeds up WebP lossless decoding by 20%. In particular, the
photographic images get 35% speedup.
Change-Id: Idb94750342a140ec05df52c07e12be4bba335adc
+ some revamp and cleanup of the alpha-filter trial loop
+ EncodeAlphaInternal() now just takes a FilterTrial param
Change-Id: Ief84385083b1cba02678bbcd3dbf707245ee962f
* 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
rather than symlink the webm/vpx terms, use the same header as libvpx to
reference in-tree files
based on the discussion in:
https://codereview.chromium.org/12771026/
Change-Id: Ia3067ecddefaa7ee01550136e00f7b3f086d4af4
(cherry picked from commit d640614d54)
The auto-infer logic of detecting the 'Alpha' use case
(via check '(palette[i] & 0x00ff00ffu) != 0' is failing
for this corner case image with all black pixels (rgb = 0)
and different Alpha values.
-> switch generic use-LUT detection
Change-Id: I982a8b28c8bcc43e3dc68ac358f978a4bcc14c36
(cherry picked from commit afa3450c11)
Added 1 pixel cache for palette colors for faster lookup.
This will speedup images that require ApplyPalette by 6.5% for lossless
compression.
Change-Id: Id0c5174d797ffabdb09905c2ba76e60601b686f8
(cherry picked from commit 742110ccce)
Start VP8EncLoop/VP8EncTokenLoop only if VP8EncStartAlpha succeeded.
Change-Id: Id1faca3e6def88102329ae2b4974bd4d6d4c4a7a
(cherry picked from commit 67708d6701)
new option: -blend_alpha 0xrrggbb
also: don't force picture.use_argb value for lossless. Instead,
delay the YUVA<->ARGB conversion till WebPEncode() is called.
This make the blending more accurate when source is ARGB
and lossy compression is used (YUVA).
This has an effect on cropping/rescaling. E.g. for PNG, these
are now done in ARGB colorspace instead of YUV when lossy compression
is used.
Change-Id: I18571f1b1179881737a8dbd23ad0aa8cddae3c6b
(cherry picked from commit e7d9548c9b)
Tuned the cross_color transform parameter (step) for lower quality
levels. This change gives speedup of 20% at lower qualities (25) and 10% at
moderate quality level (50) with a loss of 0.25% in compression density.
Also removed TODO for cross_color transform. Observed good correlation of
this with the predict transform.
Change-Id: I8a1044e9f24e6a5f84295c030fd444d0eec7d154
rather than symlink the webm/vpx terms, use the same header as libvpx to
reference in-tree files
based on the discussion in:
https://codereview.chromium.org/12771026/
Change-Id: Ia3067ecddefaa7ee01550136e00f7b3f086d4af4
The auto-infer logic of detecting the 'Alpha' use case
(via check '(palette[i] & 0x00ff00ffu) != 0' is failing
for this corner case image with all black pixels (rgb = 0)
and different Alpha values.
-> switch generic use-LUT detection
Change-Id: I982a8b28c8bcc43e3dc68ac358f978a4bcc14c36
Added 1 pixel cache for palette colors for faster lookup.
This will speedup images that require ApplyPalette by 6.5% for lossless
compression.
Change-Id: Id0c5174d797ffabdb09905c2ba76e60601b686f8
'mem' was being offset once by DO_ALIGN() then shifted 'nz_size' which
would end up accounting for more than ALIGN_CST and exceed the allocation.
broken since:
9bf3129 align VP8Encoder::nz_ allocation
Change-Id: I04a4e0bbf80d909253ce057f8550ed98e0cf1054
new option: -blend_alpha 0xrrggbb
also: don't force picture.use_argb value for lossless. Instead,
delay the YUVA<->ARGB conversion till WebPEncode() is called.
This make the blending more accurate when source is ARGB
and lossy compression is used (YUVA).
This has an effect on cropping/rescaling. E.g. for PNG, these
are now done in ARGB colorspace instead of YUV when lossy compression
is used.
Change-Id: I18571f1b1179881737a8dbd23ad0aa8cddae3c6b
user can now call WebPEncode() with any YUVA or ARGB format, for
lossy or lossless compression
also: simplified error reporting, which is done in WebPPictureARGBToYUVA()
and WebPPictureYUVAToARGB()
Change-Id: Ifb68909217175bcf5a050e5c68d06de9849468f7
(cherry picked from commit 07d87bda1b)
Saturation was done on input coeff, not quantized one.
This saturation is not absolutely needed: output of FTransformWHT
is in range [-16320, 16321]. At quality 100, max quantization steps is 8,
so the maximal range used by QuantizeBlock() is [-2040, 2040].
But there's some extra bias (mtx->bias_[] and mtx->sharpen_[]) so
it's better to leave this saturation check for now.
addresses issue #145
Change-Id: I4b14f71cdc80c46f9eaadb2a4e8e03d396879d28
* merge cost calculation functions (BitsEntropy() and HuffmanCost())
* have HistogramAdd() specialized into separate functions
* use threshold to bail-out early
* revamp code a bit
* also: save memory by freeing free(histogram_image)
Change-Id: I8ee5d2cfa1462d5d6ea6361f5c89925a3720ef55
This is required for WebP lossy+Alpha images, where Alpha channel is taking
60-70% of the compression (CPU) cycles.
Also evaluated on 1000 PNG corpus and overall compression speed
is 15-40% better for lossy (PNG+Alpha) compression.
The pure lossless compression numbers are almost same (or little
better) with this change.
Change-Id: I9e5ae7372ed6227a9a5b64cd9cff84c747195a57
using token-buffer (that is: slightly more memory. O(output_size))
This change is ON by default. To return to previous behaviour, use
'cwebp -low_memory' or set config.low_memory to true.
Side-effect of this new mode: it forces 1 partition only (which was
default anyway), and makes some statistics about the bitstream
no longer available. cwebp will no longer report 'intra4-coeffs', etc.
This mode also doesn't work (yet) with multi-pass, and -low_memory
is currently forced for multi-pass.
also: reversed the flag: USE_TOKEN_BUFFER -> DISABLE_TOKEN_BUFFER
also: fixed the kAverageBytesPerMB estimate
Change-Id: I4ea80382038d6df4309663e0cb7bd88d9bca9cf1
broken since:
ad25032 Merge "multi-threaded alpha encoding for lossy"
this produced an error due to an empty VP8TBuffer struct.
Change-Id: I640809d07d20092c1d660e2b59b58a62a12e4371
new option: 'cwebp -mt ...'
new config flag: config.thread_level
(allowed thread_level are 0 or 1 for now. Maybe more later...)
If -mt is activated (and WEBP_USE_THREAD is used for compile), the alpha-compression
will be done in parallel to RGB coding for lossy. Can save quite a bit of latency...
Has no effect for lossless encoding.
Change-Id: I769d0bf90e7380cf99344ad62cd77277f4df5a46
signed integer overflow behavior is undefined, split PrefixEncode() to
two branches to avoid this.
Change-Id: I6e2761d0d77f0aaceafdc4e07232e089c22beb64
This option remaps internal parameters to better match
the expected compression curve of JPEG and produce output files
of similar size, but with better quality.
Change-Id: I96a1cbb480b1f6a0c6845a23c33dfd63f197b689
also change lossless encoder logic, which was relying on explicit
NULL return from WebPSafeMalloc(0)
renamed function to CheckSizeArgumentsOverflow() explicitly
addresses issue #138
Change-Id: Ibbd51cc0281e60e86dfd4c5496274399e4c0f7f3
