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Diffstat (limited to 'src/3rdparty/libwebp/README')
| -rw-r--r-- | src/3rdparty/libwebp/README | 50 |
1 files changed, 46 insertions, 4 deletions
diff --git a/src/3rdparty/libwebp/README b/src/3rdparty/libwebp/README index dd50185..381b927 100644 --- a/src/3rdparty/libwebp/README +++ b/src/3rdparty/libwebp/README @@ -4,7 +4,7 @@ \__\__/\____/\_____/__/ ____ ___ / _/ / \ \ / _ \/ _/ / \_/ / / \ \ __/ \__ - \____/____/\_____/_____/____/v0.4.4 + \____/____/\_____/_____/____/v0.5.0 Description: ============ @@ -15,7 +15,8 @@ as well as the command line tools 'cwebp' and 'dwebp'. See http://developers.google.com/speed/webp -Latest sources are available from http://www.webmproject.org/code/ +The latest source tree is available at +https://chromium.googlesource.com/webm/libwebp It is released under the same license as the WebM project. See http://www.webmproject.org/license/software/ or the @@ -53,6 +54,12 @@ Please refer to makefile.unix for additional details and customizations. Using autoconf tools: --------------------- +Prerequisites: +A compiler (e.g., gcc), make, autoconf, automake, libtool. +On a Debian-like system the following should install everything you need for a +minimal build: +$ sudo apt-get install gcc make autoconf automake libtool + When building from git sources, you will need to run autogen.sh to generate the configure script. @@ -152,6 +159,8 @@ Options: default, photo, picture, drawing, icon, text -preset must come first, as it overwrites other parameters + -z <int> ............... activates lossless preset with given + level in [0:fast, ..., 9:slowest] -m <int> ............... compression method (0=fast, 6=slowest) -segments <int> ........ number of segments to use (1..4) @@ -179,13 +188,15 @@ Options: -alpha_method <int> .... transparency-compression method (0..1) -alpha_filter <string> . predictive filtering for alpha plane, one of: none, fast (default) or best - -alpha_cleanup ......... clean RGB values in transparent area + -exact ................. preserve RGB values in transparent area -blend_alpha <hex> ..... blend colors against background color expressed as RGB values written in hexadecimal, e.g. 0xc0e0d0 for red=0xc0 green=0xe0 and blue=0xd0 -noalpha ............... discard any transparency information -lossless .............. encode image losslessly + -near_lossless <int> ... use near-lossless image + preprocessing (0..100=off) -hint <string> ......... specify image characteristics hint, one of: photo, picture or graph @@ -268,13 +279,16 @@ Use following options to convert into alternate image formats: -nofilter .... disable in-loop filtering -nodither .... disable dithering -dither <d> .. dithering strength (in 0..100) + -alpha_dither use alpha-plane dithering if needed -mt .......... use multi-threading -crop <x> <y> <w> <h> ... crop output with the given rectangle - -scale <w> <h> .......... scale the output (*after* any cropping) + -resize <w> <h> ......... scale the output (*after* any cropping) + -flip ........ flip the output vertically -alpha ....... only save the alpha plane -incremental . use incremental decoding (useful for tests) -h ....... this help message -v ....... verbose (e.g. print encoding/decoding times) + -quiet ....... quiet mode, don't print anything -noasm ....... disable all assembly optimizations Visualization tool: @@ -294,6 +308,7 @@ Options are: -nofancy ..... don't use the fancy YUV420 upscaler -nofilter .... disable in-loop filtering -dither <int> dithering strength (0..100), default=50 + -noalphadither disable alpha plane dithering -mt .......... use multi-threading -info ........ print info -h ....... this help message @@ -344,6 +359,10 @@ Options: or lossless compression heuristically -q <float> ............. quality factor (0:small..100:big) -m <int> ............... compression method (0=fast, 6=slowest) + -min_size .............. minimize output size (default:off) + lossless compression by default; can be + combined with -q, -m, -lossy or -mixed + options -kmin <int> ............ min distance between key frames -kmax <int> ............ max distance between key frames -f <int> ............... filter strength (0=off..100) @@ -366,6 +385,29 @@ or using autoconf: $ ./configure --enable-everything $ make +Comparison of animated images: +============================== +Test utility anim_diff under examples/ can be used to compare two animated +images (each can be GIF or WebP). + +Usage: anim_diff <image1> <image2> [options] + +Options: + -dump_frames <folder> dump decoded frames in PAM format + -min_psnr <float> ... minimum per-frame PSNR + -raw_comparison ..... if this flag is not used, RGB is + premultiplied before comparison + +Building: +--------- +With the libgif development files and a C++ compiler installed, anim_diff can +be built using makefile.unix: +$ make -f makefile.unix examples/anim_diff + +or using autoconf: +$ ./configure --enable-everything +$ make + Encoding API: ============= |