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
