huff_image_size was a size_t (=32 bits with 32-bit builds) which could
rollover causing an incorrectly sized allocation and a crash in lossless
encoding.
fixes issue #128
Change-Id: I0f20cee98c29b2b40b02607930b6b7a7ca56996d
Added a threshold of MAX_COLORS_FOR_GRAPH for color-palettes, above
which the graph hint is ignored.
Change-Id: Ia5d7f45e52731b6eaf2806999d6be82861744fd3
For low-color images, it may be better to not use color-palettes.
Users should treat this as one another hint (as with Photo &
Picture) and another parameter for tuning the compression density.
The optimum compression can still be obtained by running (outer loop)
compression with all possible tunable parameters.
Change-Id: Icb1a4face2a84774e16e801aee4a8ae97e232e8a
* Extend AuxStats with new fields
it's slightly ABI-incompatible, but i guess it's ok for 0.1.99+
I expect to add more stats later, possibly (predictor stats, etc.)
* Have cwebp report the features used by lossless
compression (either for alpha or full lossless coding)
* Print the PSNR for alpha (useful in case of -alpha_q)
* clean-up alpha.c signatures
+ misc cleanup (added const '* const ptr', etc.)
Change-Id: I157a21581f1793cb0c6cc0882e7b0a2dde68a970
This limit corresponds to default histo_bits=3 for images upto sizes 400x400.
Any image higher than this dimension will bump up the histo_bits to 4 internally.
Change-Id: Ic8ba3dcd50e9c588cbbc4a0457289086498ff4ee
Fix inequality assertion on number of palette colors.
Fix inequality assertion test in BackwardReferencesHashChainFollowChosenPath.
Change-Id: Ie3242f1bbeaf96db91b839b6732ccce2634cebf3
Used when we don't code a Huffman Image.
-> Simplify the code quite some because we don't have to
deal with special cases of histo bits
Change-Id: I0c3f46cbf3b501e021c093e07253e7404c01ff4f
Updated histo_bits to 3 from 4 and changed the quality threshold for inner loop for HashChainFindCopy.
Impact: 0.5%-0.8% better bpp with 15%-20% hit on encoding throughput
at default encoding settings.
Change-Id: I316ef88403148b1e19036fa0817d944eb0301255
Ensure that the lossless bit-stream doesn't allow for such cases and
safe-gaurd decoder against indefinite recursion.
Change-Id: Ia6d7f519291de8739f79a977a5800982872aae71
VP8-lossy will now avoid writing an ALPH chunk if the
alpha values are trivial.
+ changed DumpPicture() accordingly in cwebp
+ prevented the -d option to be active with lossless
(DumpPicture wouldn't work).
Change-Id: I34fdb108a2b6207e93fa6cd00b1d2509a8e1dc4b
Change the lossless signature to 0x2f
Add 1 bit indicator for 'droppable (or trivial) alpha)'.
Add 3 bit lossless version (for future extension like yuv support).
Change the sub-resolution information to 3 bits implying range [2 .. 9]
Change-Id: Ic7b8c069240bbcd326cf5d5d4cd2dde8667851e2
* RIFF header is omitted
* rename NewVP8LEncoder and DeleteVP8Encoder
* change the signature to take a "const WebPPicture*"
(it was non-const just because we were setting some error potentially)
* made the pic_ field const in VP8LEncoder too.
* trap the bitwriter::error_ too
* simplify some signatures to take WebPPicture* instead
of unneeded VP8LEncoder*
VP8LEncodeStream() will be called directly to compress alpha channel
header-less.
Change-Id: Ibceef63d2b3fbc412f0dffc38dc05c2dee6b6bbf
-> lot of simplifications ensue and we should be able to get rid of
ClearHuffmanTreeIfOnlyOneSymbol() too, in a subsequent patch.
Change-Id: Ic4c51d05e4b1970e37f94ffd85fae6a02e4a6422
Allocate big chunk of memory in GetHuffBitLengthsAndCodes, instead of allocating in a loop.
Also fixed the potential memleak.
Change-Id: Idc23ffa306f76100217304444191a8d2fef9c44a
The size written in VP8L header should be without padding.
(Also clarified this code using consts).
Change-Id: Ic6583d760c0f52ef61924ab0330c65c668a12fdc
if histogram_image_size is reduced in when writing the histogram_image
the bit arrays would leak any remaining elements. store their element
count separately.
Change-Id: I710142a11ebd4325faec7bd65c2d2572aae19307
The current implementation doesn't take care one byte
signature and associated one byte padding (for odd sized chunk).
Change-Id: I35b81d0644818cdba38189aa48c75db5f92e68f4
The new method VP8LGetBackwardReferences hides internal
heuristics used for choosing RLE or LZ77 based refs.
- Tuned VP8LHashChainFindCopy for better compression at higher Q.
- Refactored code.
- Removed the unused method VP8LVerifyBackwardReferences.
Change-Id: Ibb7bb072bab5a49a001577a20d88226f52e6c663
arrays can be passed directly as only their members are being modified.
this also reduces the allocation for bit_codes[] by taking the
sizeof(type)=2 rather than sizeof(ptr)=4/8 in one case.
Change-Id: Idad20cead58c218b58d90b71699374fefd01cad9
VP8LHistogramSet is container for pointers to histograms that
we can shuffle around. Allocation is one big chunk of memory.
Downside is that we don't de-allocate memory on-the-go during
HistogramRefine().
+ renamed HistogramRefine() into HistogramRemap(), so we don't
confuse with "HistogramCombine"
+ made VP8LHistogramClear() static.
Change-Id: Idf1a748a871c3b942cca5c8050072ccd82c7511d
* de-inline some function
* make VP8LBackwardRefs be more like a vectorwith max capacity
* add bit_cost_ field to VP8LHistogram
* general code simplifications
* remove some memmov() from HistogramRefine
* simplify HistogramDistance()
...
Change-Id: I16904d9fa2380e1cf4a3fdddf56ed1fcadfa25dc
