Before, the color cache size was chosen optimally for LZ77 and
the same value was used for RLE. Now, we optimize its value
taking both LZ77 and RLE into account.
Unfortunately, that comes with a small CPU hit.
Change-Id: I6261f04af78cf0784bb8e8fc4b4af5f566a0e071
Between each iteration we keep track of the previously found
potential merge hence less work to do.
Change-Id: I2b6237447e79443516a6111727d96c24f10bd98a
It was a bad implementation of a Lehmer random number generator
(the saturation was done wrong and mostly & was used instead of % .....).
That lead to "for" loop stuck with the same values given a specific seed,
hence wasted "for" loops (e.g. seed getting at 374988608 and modulo of 64
later leads to 0 even when updating the seed with the old formula).
As the "for" loops now always return a proper pair of histograms, their
number can greatly be reduced, hence a speedup.
Change-Id: I9f5b44d66cc96fd4824189d92276c3756c8ead5b
Previously, the stochastic method for histogram
combination could finish in a greedy way
if the number of iterations to perform so was smaller.
Except that another greedy combination was performed
afterwards ... hence wasted CPU in some cases.
Change-Id: Ic0f26873e6dc746679486b91cb35d73efee91931
The initial re-writing of this part of the code with intervals
had to be done with a complex logic (mostly intervals with a
lower and upper bound, not a constant value like now) to properly
deal with the inefficiencies of the then LZ77 algorithm.
The improvements made to LZ77 since, now allow for a simpler logic.
There were also small errors in the interval insertion logic
that lead to small inefficiencies (hence a slightly better
compression rate).
Change-Id: If079a0cafaae7be8e3f253485d9015a7177cf973
this avoids duplicates between these trees and dsp/, e.g., enc/tree.c,
dec/tree.c, making pulling the whole library source tree into one target
possible
BUG=webp:279
Change-Id: I060a614833c7c24ddd37bf641702ae6a5eef1775
The previous optimization was performing dichotomy on a function that
is anything in practice, hence a bit of randomness.
Also, two magic constants were used, one for an extra constant cost,
one for an extra linear cost. Both values/models were empirical.
A brute force search for the best cache size is now performed.
To have less CPU impact, a speed optimization is also made by not
inserting a value again and again.
This makes sense but it's also the most common case of when LZ77 is
useful hence an overall improvement sometimes.
Change-Id: I57de5750ad2313b2feecbcd15cd6e4feeb98e5c8
- 12/13/2016: version 0.5.2
This is a binary compatible release.
This release covers CVE-2016-8888 and CVE-2016-9085.
* further security related hardening in the tools; fixes to
gif2webp/AnimEncoder (issues #310, #314, #316, #322), cwebp/libwebp (issue
#312)
* full libwebp (encoder & decoder) iOS framework; libwebpdecoder
WebP.framework renamed to WebPDecoder.framework (issue #307)
* CMake support for Android Studio (2.2)
* miscellaneous build related fixes (issue #306, #313)
* miscellaneous documentation improvements (issue #225)
* minor lossy encoder fixes and improvements
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Merge tag 'v0.5.2'
libwebp-0.5.2
- 12/13/2016: version 0.5.2
This is a binary compatible release.
This release covers CVE-2016-8888 and CVE-2016-9085.
* further security related hardening in the tools; fixes to
gif2webp/AnimEncoder (issues #310, #314, #316, #322), cwebp/libwebp (issue
#312)
* full libwebp (encoder & decoder) iOS framework; libwebpdecoder
WebP.framework renamed to WebPDecoder.framework (issue #307)
* CMake support for Android Studio (2.2)
* miscellaneous build related fixes (issue #306, #313)
* miscellaneous documentation improvements (issue #225)
* minor lossy encoder fixes and improvements
* tag 'v0.5.2': (54 commits)
update ChangeLog
anim_util: quiet implicit conv warnings in 32-bit
jpegdec: correct ContextFill signature
Remove some errors when compiling the code as C++.
vwebp: clear canvas during resize w/o animation
tiffdec: restore libtiff 3.9.x compatibility
update NEWS
AnimEncoder: avoid freeing uninitialized memory pointer.
WebPAnimEncoder: If 'minimize_size' and 'allow_mixed' on, try lossy + lossless.
fix a potential overflow with MALLOC_LIMIT
bump version to 0.5.2
update AUTHORS & .mailmap
iosbuild.sh: add WebPDecoder.framework + encoder
AnimEncoder: Correctly skip a frame when sub-rectangle is empty.
Fix assertions in WebPRescalerExportRow()
fix a typo in WebPPictureYUVAToARGB's doc
systematically call WebPDemuxReleaseIterator() on dec->prev_iter_
doc: use two's complement explicitly for uint8->int8 conversion
Anim_encoder: correctly handle enc->prev_candidate_undecided_
WebPPictureDistortion(): free() -> WebPSafeFree()
...
Change-Id: I16bcf54af41ce8fad98d4fbc8aa1df58f338fc23
When try_both_modes=0 (that is: -m 0 or -m 1), and the mode is i4,
we were still sometimes falling back to (unexplored, uninitialized) i16 mode,
which resulted in a enc/dec mismatch.
This was mainly occurring for large images (when bit_limit is low enough)
We disable the fall-back by disabling bit_limit using a large MAX_COST threshold.
Change-Id: I0c60257595812bd813b239ff4c86703ddf63cbf8
(cherry picked from commit 0a3838ca77)
the min-distortion was quite too low. And we were also
considering the fully skipped macroblocks (nz=0) in the stats.
We need to have at least *some* non-zero dc coeffs (nz=0x100XXXX).
Fix also two typos in StoreMaxDelta: the v0/v1 comparison was wrong,
and the DCs[] coeffs are actually already in ZigZag order.
Change-Id: I602aaa74b36f7ce80017e506212c7d6fd9deba1f
(cherry picked from commit e4cd4daf74)
max_i4_header_bits_ could drop to zero for difficult image and trigger
a loop. Surprisingly, StatLoop() didn't have this bug.
Change-Id: Idc0f9eadef30a2b2f02041b994f25def30901e36
(cherry picked from commit 21e7537abe)
Pick the mode with the smallest alpha.
It only affects m0, in which case the mode decision is not re-examined
later in VP8Decimate(). Tests on some natural content png images show
PSNR increase as well as visual quality improvement.
Change-Id: Iea997e718cd7477160fa05eb7cfb35f4cec2fa9a
(cherry picked from commit 1377ac2ec1)
avoiding triplets of data should make it easier to write SSE2 versions.
FilterRow() can now filter all input in one single pass
-> conversion is 15-20% faster (but still overall slow compared to -pre 0)
Change-Id: I14c3215e672fdecde7ec80394e814bdc7445019f
When try_both_modes=0 (that is: -m 0 or -m 1), and the mode is i4,
we were still sometimes falling back to (unexplored, uninitialized) i16 mode,
which resulted in a enc/dec mismatch.
This was mainly occurring for large images (when bit_limit is low enough)
We disable the fall-back by disabling bit_limit using a large MAX_COST threshold.
Change-Id: I0c60257595812bd813b239ff4c86703ddf63cbf8
avoids int rollover when working with large input
BUG=webp:312
Change-Id: I6ad9f93b6c4b665c559bff87716a7b847f66a20d
(cherry picked from commit 342e15f0ce)
avoids int rollover when working with large input
BUG=webp:312
Change-Id: I2881bec2884b550c966108beeff1bf0d8ef9f76b
(cherry picked from commit 1147ab4ee7)
avoids int rollover when working with large input
BUG=webp:312
Change-Id: I693cbb295df9cf94aa89294b19c0496bdbe84d18
(cherry picked from commit de9fa5074e)
avoids int rollover when working with large input
BUG=webp:312
Change-Id: I3d7b689be8d5751248a82d1021243d80d3f67203
(cherry picked from commit deb1b83199)
the min-distortion was quite too low. And we were also
considering the fully skipped macroblocks (nz=0) in the stats.
We need to have at least *some* non-zero dc coeffs (nz=0x100XXXX).
Fix also two typos in StoreMaxDelta: the v0/v1 comparison was wrong,
and the DCs[] coeffs are actually already in ZigZag order.
Change-Id: I602aaa74b36f7ce80017e506212c7d6fd9deba1f
Make WebPPictureDistortion() only compute distortion on A/R/G/B planes, not Y/U/V(A).
(not just for SSIM, but PSNR too).
This is to avoid problems with using SSIM on U/V channels.
If Y/U/V distortion is needed, one can always use WebPPlaneDistortion() individually.
Change-Id: If8bc9c3ac12a8d2220f03224694fc389b16b7da9
When compiling as experimental, WEBP_EXPERIMENTAL_FEATURES
would not be defined because the header defining it would
not be included.
Hence runtime errors in debug mode when running:
./cwebp -lossles whatever
...
Error! Cannot encode picture as WebP
Error code: 4 (INVALID_CONFIGURATION: configuration is invalid)
(detail: WebPConfig would have a random value set for
delta_palettization as config.c does not consider
it to exist.)
Change-Id: I41761cffe81a971130ed514b195a73d1c6dac1b7
If a small hash map can be used, use it to avoid binary search.
This fist hash function that is tried works with the previous
use case of having indexed data in green.
Change-Id: I2f91cec5f3ca7e9c393fd829e69e09bab74f4e7c
The most common conditions are re-ordered and cached.
iter_min was recently introduced to make sure enough iterations
are made in cases where there are many matches (mostly uniform regions).
Now that those are properly analyzed, it becomes useless.
Change-Id: Id3010ee4ec66b84d602fcb926f91eb9155ad27f4
-Skip examining quantized levels that are too high.
-Calculate last_pos_cost only when needed.
Encoding speed for m6 is increased by about 3%;
Compression performance is neutral.
Change-Id: I8af70b049587cca0375d9b3eb00479ec7c0c842a
max_i4_header_bits_ could drop to zero for difficult image and trigger
a loop. Surprisingly, StatLoop() didn't have this bug.
Change-Id: Idc0f9eadef30a2b2f02041b994f25def30901e36
Pick the mode with the smallest alpha.
It only affects m0, in which case the mode decision is not re-examined
later in VP8Decimate(). Tests on some natural content png images show
PSNR increase as well as visual quality improvement.
Change-Id: Iea997e718cd7477160fa05eb7cfb35f4cec2fa9a
SSIM results are incompatible with previous version!
We're now averaging the SSIM value for each pixels instead of
printing a frame-level global SSIM value.
* Got rid of some old code
* switched to uint32_t for accumulation
* refactoring
SSIM calculation is ~4x faster now.
Change-Id: I48d838e66aef5199b9b5cd5cddef6a98411f5673
-print_psnr is now much faster because it doesn't use the SSIM code.
The SSIM speed-up and re-write will come later.
Change-Id: Iabf565e0a8b41651d8164df1266cfeded4ab4823
we don't need to centralize best_uv[] since target_uv[] and best_rgb_uv[]
are already centralized. The diff 'W' was just in the ~[-2,2] range, so
we can ignore the correction.
Overall speed-impact is not large, though. Around ~4% faster conversion.
Output with -pre 4 is expected to be slightly different
Change-Id: Ib59f033955577c49b084d0560108020f42d84102
also: remove the useless clipping in StoreGray()
For speed reason, the 'gray' plane was initialized with the same
value for 2x2 block. But in some cases (underlying camera noise, e.g.),
it could lead to instability during iteration, noise amplification,
and visible banding.
Using a precise (but slower) initialization solves the issue, and
since the convergence is faster, we might actually gain some speed.
Change-Id: I81c42101497e7096a8f60289d710f5a3bcb0ddea
We usually need at least 2 iterations to converge
(and usually not much more after that). Only 1 was not enough.
Change-Id: Iaf802ea81afa2596f4ba045c92f5eaff61623b7b
No need to find backward references for pixels in uniform regions
by looking at all pixels.
Only pixels at the same distance from the end need to be compared to.
Change-Id: I4f187e965f0667d3a929775726a412f7e69f6473
Constants are such that brute force is sometimes faster for some
data (mostly big images it seems).
Change-Id: I90aef536408683535e3b09ddfa2e77a9834038f6
Return key/index if the query is found, and -1 otherwise.
The benefit of this is to save a hashing computation.
Change-Id: Iff056be330f5fb8204011259ac814f7677dd40fe
The decision is based on the variance between DC values of each
sub-4x4 block. This heuristic is rather ok for predicting whether
the 2nd transform (intra-16) is going to help or not.
The decision threshold varies with quality (=quantization).
It's only used for -m 0 and -m 1, where no full RD-opt is performed.
It actually makes these modes quite faster, with RD curve much
closer to the -m 2 mode.
Change-Id: I15f972db97ba4082cbd1dfd16bee3eb2eca701a8
- 6/14/2016: version 0.5.1
This is a binary compatible release.
* miscellaneous bug fixes (issues #280, #289)
* reverted alpha plane encoding with color cache for compatibility with
libwebp 0.4.0->0.4.3 (issues #291, #298)
* lossless encoding performance improvements
* memory reduction in both lossless encoding and decoding
* force mux output to be in the extended format (VP8X) when undefined chunks
are present (issue #294)
* gradle, cmake build support
* workaround for compiler bug causing 64-bit decode failures on android
devices using clang-3.8 in the r11c NDK
* various WebPAnimEncoder improvements
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Merge tag 'v0.5.1'
libwebp-0.5.1
- 6/14/2016: version 0.5.1
This is a binary compatible release.
* miscellaneous bug fixes (issues #280, #289)
* reverted alpha plane encoding with color cache for compatibility with
libwebp 0.4.0->0.4.3 (issues #291, #298)
* lossless encoding performance improvements
* memory reduction in both lossless encoding and decoding
* force mux output to be in the extended format (VP8X) when undefined chunks
are present (issue #294)
* gradle, cmake build support
* workaround for compiler bug causing 64-bit decode failures on android
devices using clang-3.8 in the r11c NDK
* various WebPAnimEncoder improvements
* tag 'v0.5.1': (30 commits)
update ChangeLog
Clarify the expected 'config' lifespan in WebPIDecode()
update ChangeLog
Fix corner case in CostManagerInit.
gif2webp: normalize the number of .'s in the help message
vwebp: normalize the number of .'s in the help message
cwebp: normalize the number of .'s in the help message
fix rescaling bug: alpha plane wasn't filled with 0xff
Improve lossless compression.
'our bug tracker' -> 'the bug tracker'
normalize the number of .'s in the help message
pngdec,ReadFunc: throw an error on invalid read
decode.h,WebPGetInfo: normalize function comment
Inline GetResidual for speed.
Speed-up uniform-region processing.
free -> WebPSafeFree()
DecodeImageData(): change the incorrect assert
Fix a boundary case in BackwardReferencesHashChainDistanceOnly.
Make sure to consider small distances in LZ77.
add some asserts to delimit the perimeter of CostManager's operation
...
Change-Id: I44cee79fddd43527062ea9d83be67da42484ebfc
This is essentially a revert of a3611513d2
and cfbcc5ece0.
Here is what happened: there was a corruption bug that eventually
got fixed by 0174d18d8b.
But before finding the root, a3611513d2
and cfbcc5ece0 hid the bug
by not imposing length of 1 when it was actually 2 or 3 (which does help
compression as a litteral is more efficient than an offset and a length
of size 2 or 3).
Change-Id: I6f18fc1f583a51ac9d8aab2508458264047cd493
We only perform a single pass, and swap the final histograms
into the beginning of the array as we go. Therefore, they are
already at the correct place at the end of the pass.
-> HistogramCompactBins() is removed, we just truncate the array.
output is bitwise the same.
Change-Id: I9508c96dda0f8903c927a71b06af4e6490c3249c
output should bit-write the same as before, in both
low_effort and non low_effort modes.
if anything, speed is a tad faster, probably because of the
reduced memory traffic.
Change-Id: Iaa2ddcfda2aaffefe7e5b7bc89216373d1ddb194
The optimization for (len != MIN_LENGTH) actually only holds for
(len > MIN_LENGTH) but (len < MIN_LENGTH) can now happen as len can
be changed in the loop before.
Change-Id: I3f9f91a540206c80385c5fba96c3d64ab9536752
This is getting back to the old behavior which is actually better for
compression and speed with the latest patches.
Change-Id: I35884bab02589297c25d6e1e66dc5f13e05f7aa7
This was defined (slightly differently) at two places. Created a common
method and moved to utils/utils.[hc].
Change-Id: I66c3ac6dea24e0cd2c0eaa5440f3142b4dbbe23b
we don't need to store the resulting histogram, so no need to
call HistogramAddEval().
Allows some signature simplifications...
Change-Id: I3fff6c45f4a7c6179499c6078ff159df4ca0ac53
In case where the same offset is found in consecutive pixels,
the cost computation from one pixel can be re-used for the next.
Change-Id: Ic03c7d4ab95f3612eafc703349cfefd75273c3d7
and also recycle the malloc'd intervals
This avoids quite some malloc/free cycles during interval managment.
Change-Id: Ic2892e7c0260d0fca0e455d4728f261fb4c3800e
In a lot of cases, only one interval is used. This can cause
a lot of malloc/free cycles for only 56 bytes. By caching this
single interval and re-using it, we remove this cycle in most
frequent cases.
Change-Id: Ia22d583f60ae438c216612062316b20ecb34f029
In some cases, the hash chain for a function is filled several
times:
- GetBackwardReferences -> CalculateBestCacheSize ->
BackwardReferencesLz77 that computes the hash chain
- GetBackwardReferences ->
(not always) BackwardReferencesTraceBackwards ->
BackwardReferencesHashChainDistanceOnly that computes the hash
chain in a slightly different way
Speed and compression performance are slightly changed (+ or -)
but will be homogneized in a later patch.
Change-Id: I43f0ecc7a9312c2ed6cdba1c0fabc6c5ad91c953
Instead of comparing all the following pixels over len (which can
frequently reach the maximum MAX_LENGTH=4096 for some images),
intervals are stored and compared.
Change-Id: I0dafef6cc988dde3c1c03ae07305ac48901d60ee
The old implementation in enc/near_lossless.c performing a separate
preprocessing step is used only when a prediction filter is not used,
otherwise a new implementation integrated into lossless_enc.c is used.
It retains the same logic for converting near lossless quality into max
number of bits dropped, and for adjusting the number of bits based on
the smoothness of the image at a given pixel. As before, borders are not
changed.
Then, instead of quantizing raw component values, the residual after
subtract green and after prediction is quantized according to the
resulting number of bits, taking care to not cross the boundary between
255 and 0 after decoding. Ties are resolved by moving closer to the
prediction instead of by bankers’ rounding.
This results in about 15% size decrease for the same quality.
Change-Id: If3e9c388158c2e3e75ef88876703f40b932f671f
the number of segments are previously validated, but an explicit check
is needed to avoid a warning under gcc-4.9
this is similar to the changes made in:
c8a87bb AssignSegments: quiet -Warray-bounds warning
3e7f34a AssignSegments: quiet array-bounds warning
Change-Id: Iec7d470be424390c66f769a19576021d0cd9a2fd
This avoids generating file that would trigger a decoding bug
found in 0.4.0 -> 0.4.3 libwebp versions.
This reverts commit 6ecd72f845.
Change-Id: I4667cc8f7b851ba44479e3fe2b9d844b2c56fcf4
The mode's bits were not taken into account, which is ok for most of cases.
But in case of super large image, with 'easy' content, their overhead starts
mattering a lot and we were omitting to optimize for these.
Now, these mode bits have their own lambda values associated, limiting
the jerkiness. We also limit (for -m 2 only) the individual number of bits
to something that will prevent the partition 0 overflow.
removed the I4_PENALTY constant, which was a rather crude approximation.
Replaced by some q-dependent expression.
fixes issue #289
Change-Id: I956ae2d2308c339adc4706d52722f0bb61ccf18c
This is in preparation for some SSE2 code.
And generally speaking, the whole SSIM code needs some
revamp: we're not averaging the SSIM value at each pixels
but just computing the overall SSIM value once, for the whole
plane. The former might be better than the latter.
Change-Id: I935784a917f84a18ef08dc5ec9a7b528abea46a5
- The result is now indeed closest among possible results for all inputs, which
was not the case for bits>4, where the mapping was not even monotonic because
GetValAndDistance was correct only if the significant part of initial fit in
a byte at most twice.
- The set of results for a larger number of bits dropped is a subset of values
for a smaller number of bits dropped. This implies that subsequent
discretizations for a smaller number of bits dropped do not change already
discretized pixels, which improves the quality (changes do not accumulate)
and compression density (values tend to repeat more often).
- Errors are more fairly distributed between upwards and downwards thanks to
bankers’ rounding, which avoids images getting darker or lighter in overall.
- Deltas between discretized values are more repetitive. This improves
compression density if delta encoding is used.
Also, the implementation is much shorter now.
Change-Id: I0a98e7d5255e91a7b9c193a156cf5405d9701f16
We were not updating the current_width_, which is usually
not a problem, unless we use Delta Palette with small number
of colors
-> Addressed this re-entrancy problem by checking we have
enough capacity for transform buffer.
The problem is not currently visible, until we restrict
the number of gradient used in delta-palette to less than 16.
Then the buffers have different current_width_ and the problem
surfaces.
Change-Id: Icd84b919905d7789014bb6668bfb6813c93fb36e
The code and logic is unified when computing bit entropy + Huffman cost.
Speed-wise, we gain 8% for lossless encoding.
Logic-wise, the beginning/end of the distributions are handled properly
and the compression ratio does not change much.
Change-Id: Ifa91d7d3e667c9a9a421faec4e845ecb6479a633
setting all transparent pixels to black rather than the "flatten" method.
0.3% smaller filesize on the 1000 PNGs if alpha cleanup is used (before: 18685774, after: 18622472)
Change-Id: Ib0db9e7ccde55b36e82de07855f2dbb630fe62b1
The functions containing magic constants are moved out of ./dsp .
VP8LPopulationCost got put back in ./enc
VP8LGetCombinedEntropy is now unrefined (refinement happening in ./enc)
VP8LBitsEntropy is now unrefined (refinement happening in ./enc)
VP8LHistogramEstimateBits got put back in ./enc
VP8LHistogramEstimateBitsBulk got deleted.
Change-Id: I09c4101eebbc6f174403157026fe4a23a5316beb
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
