We compact the palette by weighted distance, favoring the green channel.
Average gain on paletted file is ~0.5%, with gain up to 6-7% on some favorable cases.
Encoding speed is unaffected.
Disabled for alpha (or any single-channel input)
Also: always use quality=20 for EncodePalette() since it
doesn't make any real difference.
Change-Id: I19fb14316a366f139a941b45aef5663a33c905e1
SSE2 version is 2.1x faster
This is used to transfer the alpha plane to green channel before lossless compression.
Change-Id: I01d9df0051c183b1ff5d6eb69961d4f43e33141a
Don't combine the Histograms that have trivial (single valued A, R & B)
symbols.
Following is the compression savings data along with compression time (before
& after) per image.
Before After
bpp, rate(MP/s) bpp, rate(MP/s)
Q=25, method = 4 2.508, 1.807 2.499, 1.916
Q=50, method = 4 2.460, 1.488 2.456, 1.512
Q=75, method = 4 2.452, 1.078 2.450, 1.092
Q=25, method = 5 2.505, 1.398 2.496, 1.383
Q=50, method = 5 2.458, 1.170 2.453, 1.143
Q=75, method = 5 2.453, 0.886 2.450, 0.855
This change provides 0.1-0.4% compression gains and speeds up the lossless
compression for the default method=4 (the drop in compression speed is between 1-3.5% for method=5).
Change-Id: Idfd88c2092f37afacd26a97097b3053f8183953a
Tested on 1000 pngs corpus with quality 90-100 it gives ~0.15% improvement
in compression density and ~7% speed up.
Change-Id: I460f56c96707edb3c1f0b51a024e5122e10458df
iOS 5 support isn't available in the Xcode 6 install; iOS 6 covers
phones starting at the 3GS, so should be a reasonable base line
Change-Id: Ie5603c9e30cb52114b372509e183febbf679a69a
* We don't need to change DecodeAlpha, since incremental
decoding is not useful for Alpha (we already decode
progressively along the RGB)
* Similarly, we don't do incremental decoding for level>0 planes:
the metadata don't turn into visible pixel (only the ones in level0), so...
(No visible speed change)
Change-Id: I2fd4b9ba227561a7dbede647686584b752be7baa
- don't call VP8LClear() when there's no error (and let the caller do it)
- only initialize output once if state_ is not READ_DATA
- don't over-set dec->status_ = READ_DATA
- don't re-set dec->status_ if DecodeImageStream() fails
- remove unneeded dec->action_ field
- make ReadImageInfo() check br->eos_
- use ErrorStatusLossless() more consistently
Change-Id: Ica6e4b1c82e3fce8b1ce0274def551a886b73b0b
For some GIF images, the first frame is missing the corresponding
graphic control extension. For such cases, we were never calling
GetBackgroundColor(), and default background color value (white) was being used
incorrectly.
So, we call GetBackgroundColor() when we encounter the first image
descriptor instead, to make sure that it is always called.
Change-Id: I00fc8e943d8a0c1578dcd718f3e74dec7de4ed61
Optimize the decoding for region that have trivial literal codes.
The trivial literal is defined as huffman image with Red, Blue and Alpha
huffman trees with only single code values.
This speeds up lossless decoding by 3%
Change-Id: I0204949917836f74c0eb4ba5a7f4052a4797833b
put WebPMuxConfig on the stack in main() rather than allocating it in
InitializeConfig(); removes a level of indirection there.
Change-Id: I81d386f7472ebbd322dd3fdbfda9d78dbeb62a66
* We were re-doing most of the work in plain-C as 'left-over'.
* we were always returning has_alpha = true because of a bad mask all_0xff
These bugs were conservative and silent, in the sense that we were 'just' doing
more work than necessary.
Now, the SSE2 version is really 2x faster than the C version.
Change-Id: I6c8132a267fe3c7a3d1fa70e7a5fcd10719543fa
