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
Updated the near-lossless level mapping and make it correlated to lossy
quality i.e 100 => minimum loss (in-fact no-loss) and the visual-quality loss
increases with decrease in near-lossless level (quality) till value 0.
The new mapping implies following (PSNR) loss-metric:
-near_lossless 100: No-loss (bit-stream same as -lossless).
-near_lossless 80: Very very high PSNR (around 54dB).
-near_lossless 60: Very high PSNR (around 48dB).
-near_lossless 40: High PSNR (around 42dB).
-near_lossless 20: Moderate PSNR (around 36dB).
-near_lossless 0: Low PSNR (around 30dB).
Change-Id: I930de4b18950faf2868c97d42e9e49ba0b642960
Enable the WebP near-lossless feature by pre-processing the image to smoothen
the pixels.
On a 1000 PNG image corpus, for which WebP lossless (default settings) gets
25% compression gains, following is the performance of near-lossless feature
at various '-near_lossless' levels:
-near_lossless 90: 30% (very very high PSNR 54-60dB)
-near_lossless 75: 38% (very high PSNR 48-54dB)
-near_lossless 50: 45% (high PSNR 42-48dB)
-near_lossless 25: 48% (moderate PSNR 36-42dB)
-near_lossless 10: 50% (PSNR 30-36dB)
WebP near-lossless is specifically useful for discrete-tone images like
line-art, icons etc.
Change-Id: I7d12a2c9362ccd076d09710ea05c85fa64664c38
This compresses the uimage using lossless compression and controlable
decimating pre-process.
Code is under WEBP_EXPERIMENTAL_FEATURE while it's being experimented with.
Change-Id: I8b7f4cfcc3c6afc52a556102842bdbb045ed5ee8
new options:
dwebp -alpha_dither
vwebp -noalphadither
When the source was marked as quantized, we use a threshold-averaging
filter to smooth the decoded alpha plane.
Note: this option forces the decoding of alpha data in one pass, and
might slow the decoding a bit.
The new field in WebPDecoderOptions struct is 'alpha_dithering_strength'
(0 by default, means: off). Max strength value is '100'.
Change-Id: I218e21af96360d4781587fede95f8ea4e2b7287a
* allow reading from stdin for dwebp / vwebp
* allow writing to stdout for gif2webp
by introducing a new function ExUtilReadFromStdin()
Example use: cat in.webp | dwebp -o - -- - > out.png
Note that the '-- -' option must appear *last*
(as per general fashion for '--' option parsing)
Change-Id: I8df0f3a246cc325925d6b6f668ba060f7dd81d68
These are presets for lossless coding, similar to zlib.
The shortcut for lossless coding is now, e.g.:
cwebp -z 5 in.png -o out_lossless.webp
There are 10 possible values for -z parameter:
0 (fastest, lowest compression)
to 9 (slowest, best compression)
A reasonable tradeoff is -z 6, e.g.
-z 9 can be quite slow, so use with care.
This -z option is just a shortcut for some pre-defined
'-lossless -m xx -q yy' combinations.
Change-Id: I6ae716456456aea065469c916c2d5ca4d6c6cf04
New API options: WebPDecoderOptions.flip and 'dwebp -flip ...'
it uses negative stride trick.
Also changed the decoder code to support user-supplied
buffers with negative stride, independently of the
WebPDecoderOptions.flip value.
Change-Id: I4dc0d06f0c87e51a3f3428be4fee2d6b5ad76053
from man-pages (7):
provides a comma-separated list of related man pages, ordered by section
number and then alphabetically by name, possibly followed by other
related pages or documents. Do not terminate this with a period.
Change-Id: I6763b3b3a89f3c2e9ed5c1a4e9d05fb9ce85dd40
this enables webpmux to accept input files starting with '-' when using
-get/-set/-strip; -info & -frame expect an input file as one of their
parameters so no changes are necessary there.
Change-Id: I154eb6dc388258a7fb743ec76ba869bf9589be1b
This is to discourage generation of animated WebP images with ICC
profile, as
the real-world use-case for such images is rare at best.
Output of ICC/XMP metadata is now controlled by the '-metadata' option.
Change-Id: I8e3e29878c32bf46cbc661f50661bac602603c43
Even at high quality setting, the U/V quantizer step is limited
to 4 which can lead to banding on gradient.
This option allows to selectively apply some randomness to
potentially flattened-out U/V blocks and attenuate the banding.
This option is off by default in 'dwebp', but set to -dither 50
by default in 'vwebp'.
Note: depending on the number of blocks selectively dithered,
we can have up to a 10% slow-down in decoding speed it seems.
Change-Id: Icc2446007f33ddacb60b3a80a9e63f2d5ad162de
When '-mixed' option is given, each frame would be heuristically chosen
to be
encoded using lossy or lossless compression.
The heuristic is based on the number of colors in the image:
- If num_colors <= 31, pick lossless compression
- If num_colors >= 194, pick lossy compression
- Otherwise, try both and pick the one that compresses better.
Change-Id: I908c73493ddc38e8db35b7b1959300569e6d3a97
-> helps debanding (sky, gradients, etc.)
This dithering can only be triggered when using -preset photo
or -pre 2 (as a preprocessing). Everything is unchanged otherwise.
Note that this change is likely to make the perceived PSNR/SSIM drop
since we're altering the input internally.
Change-Id: Id8d4326245d9b828141de162c94ba381b1fa5813
We use the 'do not blend' option for creating independent frames.
We also mark the already independent frames as 'do not blend'.
This bounds the maximum number of frames that need to be decoded to
decode a given frame, thus leading to a much better decoding performance.
Change-Id: I7cef98af2b53751ec36993fd2bd54f7f4c4aad2b
Doesn't work with WIC
+ redirect some info messages from stdout to stderr
+ fix the error reporting upon output-writing error
Change-Id: I92b8bd7a15e656a3f3cdfbf56299f024e39453f8
new option: -blend_alpha 0xrrggbb
also: don't force picture.use_argb value for lossless. Instead,
delay the YUVA<->ARGB conversion till WebPEncode() is called.
This make the blending more accurate when source is ARGB
and lossy compression is used (YUVA).
This has an effect on cropping/rescaling. E.g. for PNG, these
are now done in ARGB colorspace instead of YUV when lossy compression
is used.
Change-Id: I18571f1b1179881737a8dbd23ad0aa8cddae3c6b
using token-buffer (that is: slightly more memory. O(output_size))
This change is ON by default. To return to previous behaviour, use
'cwebp -low_memory' or set config.low_memory to true.
Side-effect of this new mode: it forces 1 partition only (which was
default anyway), and makes some statistics about the bitstream
no longer available. cwebp will no longer report 'intra4-coeffs', etc.
This mode also doesn't work (yet) with multi-pass, and -low_memory
is currently forced for multi-pass.
also: reversed the flag: USE_TOKEN_BUFFER -> DISABLE_TOKEN_BUFFER
also: fixed the kAverageBytesPerMB estimate
Change-Id: I4ea80382038d6df4309663e0cb7bd88d9bca9cf1
new option: 'cwebp -mt ...'
new config flag: config.thread_level
(allowed thread_level are 0 or 1 for now. Maybe more later...)
If -mt is activated (and WEBP_USE_THREAD is used for compile), the alpha-compression
will be done in parallel to RGB coding for lossy. Can save quite a bit of latency...
Has no effect for lossless encoding.
Change-Id: I769d0bf90e7380cf99344ad62cd77277f4df5a46
This option remaps internal parameters to better match
the expected compression curve of JPEG and produce output files
of similar size, but with better quality.
Change-Id: I96a1cbb480b1f6a0c6845a23c33dfd63f197b689
It will decode to raw (flat) YUV format, similar to what
cwebp can take as input. Makes the PSNR/SSIM calculation easier.
Change-Id: Iebfaedfc0bedc70c169b24ae4aabc701488d0644
currently has no effect except to disable metadata extraction from the
input when the value is 'none'.
Change-Id: Ic50d4c9d634cc1f6b72ae4e130e99736c85a6477
Now, its: +duration+xoffset+yoffset+disposal
+disposal can be omitted and will default to +0 (NONE)
additionally, +xoffset+yoffset can be omitted and will default to +0+0
Change-Id: I62138c9f675d4fc4408305babbcd485cb32b73d3
- Allow a duration of 0
- Rename LOOP chunk to ANIM and add the background color field to it.
- Add a disposal method field for each animation frame.
- Modify webpmux.c binary interface to allow the input of background color
and disposal methods. Also make '-loop' and '-bgcolor' arguments optional
with some default values.
Change-Id: I807372a61cdb8a0d3080ae3552caf2848070bf4d
- Also, use the term 'fragments' instead of 'tiling' in code
- This makes code consistent with the spec.
Change-Id: Ibeccffc35db23bbedb88cc5e18e29e51621931f8
Use separate fourCCs "XMP " and "EXIF" instead of a common "META"
Also, some refactorization in webpmux.c
Change-Id: Iad3337e5c1b81e785c60670ce28b1f536dd7ee31
LSIM stands for "local similarity": before matching
a compressed pixel to the source, we search around in the source
and minimise the squared error. So, this is close to PSNR calculation,
but mitigates some of its limitations (pure translation and noise for instance).
There's a new -print_lsim option to cwebp too.
Change-Id: Ia38561034c7a90e71d2ea0f55bb1de527eda245b
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
retains the alpha channel rather than stripping it as with PPM.
display from ImageMagick can render the files
Change-Id: I4f3a5d332937e0aeaf4e3fbd214fdae3b5382fb8
the extended file format is still under development and related
libs/binaries are not fit for release
configure:
--enable/disable-libwebpmux; default is disabled.
makefile.unix:
src/mux/libwebpmux.a and examples/webpmux must be explicitly specified
Makefile.vc:
$(DIRLIB)\libwebpmux.lib and $(DIRBIN)\webpmux.exe must be explicitly
specified
Change-Id: I8246746b256010dd2a2e4de58291222d7eaf0457
- send errors to stderr
- send help to stdout
- add image size to webpmux -info output and send to stdout
- correct webpmux exit values
Change-Id: Ifd8e8493aab33a82765f7b7903cef345d96da9ae
These will report the 7x7-averaged PSNR or SSIM, using the
new internal function WebPPictureDistortion().
This is for information only. These flags have no encoding impact.
+misc opportunistic cosmetics
Change-Id: I64c0a7eca679134d39062e438886274b22bb643f
to 'clean up' the fully-transparent area and make it more compressible
new cwebp flags: -alpha_cleanup (off by default, since gain is not 100% guaranteed)
Change-Id: I74d77e1915eee146584cd61c9c1132a41db922eb
.. where only 2 filtering modes are potentially
tried, instead of all of them. This is fast than the exhaustive 'best'
mode, and not much worse.
Options for cwebp are:
-alpha_filter none
-alpha_filter fast (<- default)
-alpha_filter best (<- slow)
Change-Id: I8cb90ee11b8f981811e013ea4ad5bf72ba3ea7d4
Add predictive filtering option for Alpha plane.
Valid range for filter option is [0, 5] corresponding to prediction
methods none, horizontal, vertical, gradient & paeth filter.
The prediction method 5 will try all the prediction methods (0 to 4)
and pick the prediction method that gives best compression.
Change-Id: I9244d4a9c5017501a9696c7cec5045f04c16d49b
Updated cwebp (Webp Encoder) binary to support Alpha encoding.
Modified man page and WebP container spec appropriately.
Change-Id: I52f6a5cb3e870c386591e9a7776293fa6a8fb04b
escape '-'s
use consistent section names
webpmux.1:
document -loop
create subsections for each OPTION group
Change-Id: If41dc24d80e4a662024e82697d8d2cc4e194a35d
Although it degrades quality, this option is useful to avoid the 512k
limit for partition #0.
If not enough to reach the lower bound of 4bits per macroblock header,
one should also limit the number of segments used (down to -segments 1)
See the man file for extra details.
Change-Id: Ia59ffac13176c85b809ddd6340d37b54ee9487ea
To be enabled with the flag WEBP_USE_THREAD.
For now it's only available on unix (pthread), when using Makefile.unix
Will be switched on more generally later.
In-loop filtering and output (=rescaling/yuv->rgb conversion)
is done in parallel to bitstream decoding, lagging 1 row behind.
Example:
examples/dwebp bryce.webp -v
Time to decode picture: 0.680s
examples/dwebp bryce.webp -v -mt
Time to decode picture: 0.515s
Change-Id: Ic30a897423137a3bdace9c4e30465ef758fe53f2
You can now use WebPDecBuffer, WebPBitstreamFeatures and WebPDecoderOptions
to have better control over the decoding process (and the speed/quality tradeoff).
WebPDecoderOptions allow to:
- turn fancy upsampler on/off
- turn in-loop filter on/off
- perform on-the-fly cropping
- perform on the-fly rescale
(and more to come. Not all features are implemented yet).
On-the-fly cropping and scaling allow to save quite some memory
(as the decoding operation will now scale with the output's size, not
the input's one). It saves some CPU too (since for instance,
in-loop filtering is partially turned off where it doesn't matter,
and some YUV->RGB conversion operations are ommitted too).
The scaler uses summed area, so is mainly meant to be used for
downscaling (like: for generating thumbnails or previews).
Incremental decoding works with these new options.
More doc to come soon.
dwebp is now using the new decoding interface, with the new flags:
-nofancy
-nofilter
-crop top left width height
-scale width height
Change-Id: I08baf2fa291941686f4ef70a9cc2e4137874e85e
For now, SSE2 functions are compiled a-minima: only on platforms
where __SSE2__ is defined. Let's later add some autoconf-based
config to enable/disable at will.
One can disable SSE2 at run-time by hooking-up VP8GetInfo.
There is a new option "-noasm" in cwebp for that.
Output should be binary the same between C and SSE2 version. If not,
that's a bug!
patch by Christian Duvivier (cduvivier at google dot com)
Change-Id: Iae006c3cdcb7e8280e846cedb94d239dab1e42ae
