The previous priority system used a heap which was too heavy to
maintain (what was gained from insertions / deletions was lost
due to a linear that still happened on the heap for invalidation).
The new structure is a priority queue where only the head is
ordered.
Change-Id: Id13f8694885a934fe2b2f115f8f84ada061b9016
SimpleQuantize()
it's now a single function, that reconstructs the intra4x4 block during the scan
The I4_PENALTY had to be adjusted.
Overall, result is better quality-wise (esp. at q < 50), and a tad faster too.
method #0, #1 and #3+ are unchanged
Change-Id: If262aeb552397860b3dd532df8df6b1357779222
Gives 0.9% smaller (2.4% compared to before alpha cleanup) size on the 1000 PNGs dataset:
Alpha cleanup before: 18856614
Alpha cleanup after: 18685802
For reference, with no alpha cleanup: 19159992
Note: WebPCleanupTransparentArea is still also called in WebPEncode. This cleanup still helps
preprocessing in the encoder, and the cases when the prediction transform is not used.
Change-Id: I63e69f48af6ddeb9804e2e603c59dde2718c6c28
The 32-bit buffers are actually rarely 64-bit aligned.
The new solution uses memcmp and is alignment agnostic.
It is also slightly faster.
Change-Id: I863003e9ee4ee8a3eed25b7b2478cb82a0ddbb20
Arrays were compared 32 bits at a time, it is now done 64 bits at a time.
Overall encoding speed-up is only of 0.2% on @skal's small PNG corpus.
It is of 3% on my initial 1.3 Mp desktop screenshot image.
Change-Id: I1acb32b437397a7bf3dcffbecbcd4b06d29c05e1
instead of per block. This prepares for a next CL that can make the
predictors alter RGB value behind transparent pixels for denser
encoding. Some predictors depend on the top-right pixel, and it must
have been already processed to know its new RGB value, so requires per
scanline instead of per block.
Running the encode speed test on 1000 PNGs 10 times with default
settings:
Before:
Compression (output/input): 2.3745/3.2667 bpp, Encode rate (raw data): 1.497 MP/s
After:
Compression (output/input): 2.3745/3.2667 bpp, Encode rate (raw data): 1.501 MP/s
Same but with quality 0, method 0 and 30 iterations:
Before:
Compression (output/input): 2.9120/3.2667 bpp, Encode rate (raw data): 36.379 MP/s
After:
Compression (output/input): 2.9120/3.2667 bpp, Encode rate (raw data): 36.462 MP/s
No effect on compressed size, this produces exactly same files. No
significant measured effect on speed. Expected faster speed from better
memory layout with scanline processing but slower speed due to needing
to get predictor mode per pixel, may compensate each other.
Change-Id: I40f766f1c1c19f87b62c1e2a1c4cd7627a2c3334
Rename the flag to exact instead of the opposite cleanup_alpha. Add the flag to
WebPConfig. Do the cleanup in the webp encoder library rather than the cwebp
binary, this will be needed for the next stage: smarter alpha cleanup for
better compression which cannot be done as a preprocessing due to depending on
predictor choices in the encoder.
Change-Id: I2fbf57f918a35f2da6186ef0b5d85e5fd0020eef
global effect is ~2% faster encoding from JPG source
and ~8% faster lossless-webp source decoding to PGM (e.g.)
Also revamped the YUVA case to first accumulate R/G/B value into 16b
temporary buffer, and then doing the UV conversion.
-> New function: WebPConvertRGBA32ToUV
Change-Id: I1d7d0c4003aa02966ad33490ce0fcdc7925cf9f5
Just for RGB24/BGR24 for now, which are the hard-to-optimize ones.
SSE2 implementation coming next.
ConvertRowToY() should go into dsp/ too, at some point.
Change-Id: Ibc705ede5cbf674deefd0d9332cd82f618bc2425
Note that ALIGN_CST is still kept different in dec/frame.c for now,
because the values is 31 there, not 15. We might re-unite these two
later.
Change-Id: Ibbee607fac4eef02f175b56f0bb0ba359fda3b87
same functionality, but better code layout.
What changed:
* don't trash the palette_[] in EncodePalette(), so it can be re-used
* split generation of image from bit-stream coding
* move all the delta-palette code to delta_palettization.c, and only have 1 entry point there WebPSearchOptimalDeltaPalette()
* minimize the number of "#ifdef WEBP_EXPERIMENTAL_FEATURES" in vp8l.c
* clarify the TransformBuffer stuff. more clean-up to come here...
This should make experimenting with delta-palettization easier and more compartimentalized.
Change-Id: Iadaa90e6c5b9dabc7791aec2530e18c973a94610
New palette compresses more than 20% better with minimum quality loss.
Tested on set of wikipedia images with command line:
cwebp -delta_palettization
Change-Id: I82ec7d513136599cd70386f607f634502eb9095d
* vertical expansion now uses bilinear interpolation
* heavily assumes that the alpha plane is decoded in full, not row-by-row
* split the RescalerExportRow and RescalerImportRow methods into Shrink
and Expand variants.
* MIPS implementation of ExportRowExpand is missing.
There's room for extra speed optim and code re-org, but let's keep that for later patches.
addresses https://code.google.com/p/webp/issues/detail?id=254
Change-Id: I8f12b855342bf07dd467fe85e4fde5fd814effdb
This makes the chains more efficient and a larger variety of data is tested.
0.02 % compression gain at q 100, 0.05 % at default quality. 0.8 % speedup by
callgrind.
0.16 % compression gain for lossy alpha ?!
Change-Id: I888120133352799eb14f5f602c7f40ab404bd665
using a *tmp_plane buffer to split a/r/g/b planes up appeared to
be the easiest route, compared to copy-pasting the whole code and
making it x_stride aware...
Change-Id: I0898ef1df62bd3e1713b77187b31b5eeef3832fe
Slightly faster on -m 0 -q 0, particularly for small images (50 x 75
image was 0.1 % faster on callgrind measurement).
Increases compression density by 0.005 % for the 1000 images, but small
images can improve even 0.5 % (about 4 bytes, depending on the
characteristics of the palette).
Change-Id: I94f568d396ac62a054a829abeeef3eb0af6b3f94
the x_add/x_sub increments were wrong for u/v in the upscaling case.
They shouldn't be left to the caller's discretion, but set up by
WebPRescalerInit to their exact necessary values.
-> Cleaned-up WebPRescalerInit() param list.
-> added safety asserts
-> removed the mips32/mips_r2 variant of "ImportRow" which were buggy prior
Change-Id: I347c75804d835811e7025de92a0758d7929dfc09
a total impact of 1 % on encoding speed
This allows for performance neutral removal of the binary search
in cache bits selection. This will give a small improvement in
compression density.
Change-Id: If5d4d59460fa1924ce71af977320834a47c2054a
0.21 % compression density improvement for 1000 png corpus in
lossless mode
0.50 % compression density improvement for 1000 png corpus in
lossy mode
Change-Id: I14ee8c427ae5d3e116b0ee6695fcdea3321a319d
do not do length 2 matches far away
speedup for non compressible data by inserting two literals at a time
when no matches are found
Change-Id: Ia8e033071f4186bb8148bb2bf13ca37586734aa3
Increases compression density by 0.03 % for lossy.
Speeds up at least one of the lossy alpha images by 20 %.
Palette entropy 'kludge' seems to save 1-2 % on alpha images.
Change-Id: I2116b8d81593ac8173bfba54a7c833997fca0804
share the computation between different modes
3-5 % speedup for lossless alpha
1 % for lossy alpha
no change in compression density
Change-Id: I5e31413b3efcd4319121587da8320ac4f14550b2
introduced in:
"lossless: 0.37 % compression density improvement"
Uses the statistics of red and blue histograms to decide if to run
cross color correction at all.
Improves compression density by 0.02 % or so.
Change-Id: I47429557e9cdbd9fa90c584696f241b17427d73f
No significant size degradation (+0.001 %) for 1000 image corpus
Fixes the 8 ms vs 2 ms degradation from:
"lossless: 0.37 % compression density improvement"
Change-Id: Id540169a305d9d5c6213a82b46c879761b3ca608
counting the entropy expectation for five different configurations:
palette
non-predicted
non-predicted with subtract green
predicted
predicted with subtract green
and choose the strategy with the smallest expected entropy
Change-Id: Iaaf209c0d565660a54a4f9b3959067afb9951960
