references to fragments remain, along with some superfluous checks; these
will be removed in a future commit.
Change-Id: I39fe9314900ecbc5d60e5065b65fa1b4c668af63
and apply Paeth predictor (predictor#11) for the low effort (m=0) mode.
For 1000 image PNG corpus (m=0), this change yields speedup of 25% at lower quality
range and about 10% for higher quality range.
Change-Id: I0f036b8ffe45c241e63a067cbf01527b13d8de93
most of the time, we don't need to actually move the
data.
Compression is randomly slightly different, because HistogramCompactBins() changed.
Timing is about the same.
Change-Id: Ia6af8e9780581014d6860f2b546189ac817cfad1
check for __apple_build_version__ to distinguish the two; a version
check could work as Apple bumped Xcode's to 5.x/6.x, but it's unclear
how upstream will deal with their versioning as they go 3.6+, so avoid
it for now.
Change-Id: I67cda67c4f68e262a92d805a63cc1496374be063
we don't need to store the whole distribution in order to compute the alpha
Later, we can incorporate the max_value / last_non_zero bookkeeping
in SSE2 directly.
Change-Id: I748ccea4ac17965d7afcab91845ef01be3aa3e15
this is a first step to unifying encoding/decoding cache stride
and possibly sharing the prediction functions in dsp/
With this layout, there's a little (~7%) space lost with unused samples.
But no speed change was observed.
Change-Id: I016df8cad41bde5088df3579e6ad65d884ee711e
~68% faster
reuses TM4() adding support for the additional rows, the columns were
already being done.
Change-Id: I6eac17e58cd1c636082bf7281f70f884ec399a6b
Move all the Entropy evaluation methods to lossless.c (from histogram.c).
There's slight difference in the way entropy is computed for evaluating
entropy in prediction methods and histogram (literal) for huffman trees.
Plan (later) to merge few (static) methods and reduce the code size.
This change has no impact on the compression speed/density.
Change-Id: Ife3d96a3c4a8d78a91723d9e0a8d1b78c0256a15
Remove handling for WEBP_HINT_GRAPH w.r.t use_palette flag.
The WEBP_HINT_GRAPH is now used at one place, to set the initial size of the
Bit Writer as bpp for photo images are generally larger than the graphical
images.
Change-Id: I1b9c4436c85a8f69da74c0dbcd292397323f2696
Update BackwardRefsWithLocalCache to do in-place update of backward
references w.r.t local color cache index.
No impact on the compression density or compression speed.
Change-Id: Ie066251464c3928c044e037b43df3af28b48ca30
histogram.c:
- Verified (earlier) that there's low correlation between Red & Blue colors
(particularly after applying Cross-color transform). The Bin based histogram
merge, bins on three entropies viz literal, red & blue symbols. Removing
either of blue or red increases the compression density. So keeping the bins
for red & blue sybmols.
- Keeping the compact bins method as-is. This way it's simpler to read.
huffman_encode.h: Added field comments for struct HuffmanTree and removed the TODO.
Change-Id: Ia76f7bc730079d1b3b644038c5d9931db3797f0e
Use the refs_lz77 computed (with cache_bits=0) in the method 'CalculateBestCacheSize'
to regenerate the LZ77 references corresponding to the optimum cache_bits and avoid
calling costly 'BackwardReferencesLz77' one extra time.
This change leaves the compression density unchanged and speeds up compression
by 10-15%.
Change-Id: I5a92e11788d3c3f656aa7e1fba54fb5d96ee0027
This wasn't working for this specific scenario:
- Encode an RGBA 'pic' (with trivial alpha) using lossy encoding.
(so that pic->a == NULL after import happens).
- Modify the 'pic->argb' so that it has non-trivial alpha.
- Encode the same 'pic' again.
This used to fail to encode alpha data as pic->a == NULL.
Change-Id: Ieaaa7bd09825c42f54fbd99e6781d98f0b19cc0c
- The optimal cache bits is evaluated inside the method 'VP8LGetBackwardReferences'.
- The input cache_bits to 'VP8LGetBackwardReferences' sets the maximum cache
bits to use (passing 0 implies disabling the local color cache).
- The local color cache is disabled for lowerf (<= 25) quality levels (as before).
- Enabled local color cache for palette images as well. This saves additional
0.017% bytes with a slight (2-3%) improvement in the compression speed.
- Removed 'use_2d_locality' parameter from method VP8LGetBackwardReferences, as
this option is not an option now (after we freeze the lossless bit-stream).
Change-Id: I33430401e465474fa1be899f330387cd2b466280
This is because, FlattenSimilarBlocks() replaces some opaque pixels by
transparent ones. This results in an equivalent output only if blending
is turned on for the current frame.
Change-Id: I05612c952fdbd4b3a6e0ac9f3a7d49822f0cfb9b
Updated BackwardReferencesRle method by utilizing the local color cache.
Also changed the name of method BackwardReferencesHashChain to
BackwardReferencesLz77 to reflect the LZ77 coding.
For the 1000 image corpus, this change saves 0.2% bytes
(at default settings) and is 2-5% faster to encode.
Change-Id: Ic3f288253b3bbb101a69945a80994c3fd0917f8b
Optimize backwardreferences (about 0.1% byte savings) with almost same
compression speed (3% faster on defaut compression settings).
1.) Simplified iteration logic for HashChainFindCopy.
- Remapped the iter_max constant.
2.) Simplified main for loop for BackwardReferencesHashChain
- Removed 'if' conditions for corner cases in the main loop.
- Refactored the method(AddSingleLiteral) for adding one pixel.
Change-Id: I1bc44832fd81f11e714868a13e606c8f83157e64
