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Diffstat (limited to 'src/3rdparty/libwebp/README')
| -rw-r--r-- | src/3rdparty/libwebp/README | 132 |
1 files changed, 69 insertions, 63 deletions
diff --git a/src/3rdparty/libwebp/README b/src/3rdparty/libwebp/README index 64e9f2d..c3f32c5 100644 --- a/src/3rdparty/libwebp/README +++ b/src/3rdparty/libwebp/README @@ -4,7 +4,7 @@ \__\__/\____/\_____/__/ ____ ___ / _/ / \ \ / _ \/ _/ / \_/ / / \ \ __/ \__ - \____/____/\_____/_____/____/v0.4.0 + \____/____/\_____/_____/____/v0.4.3 Description: ============ @@ -140,28 +140,30 @@ A longer list of options is available using the -longhelp command line flag: Usage: cwebp [-preset <...>] [options] in_file [-o out_file] -If input size (-s) for an image is not specified, it is assumed to be a PNG, -JPEG or TIFF file. -options: +If input size (-s) for an image is not specified, it is +assumed to be a PNG, JPEG, TIFF or WebP file. + +Options: -h / -help ............ short help -H / -longhelp ........ long help -q <float> ............. quality factor (0:small..100:big) - -alpha_q <int> ......... Transparency-compression quality (0..100). - -preset <string> ....... Preset setting, one of: + -alpha_q <int> ......... transparency-compression quality (0..100) + -preset <string> ....... preset setting, one of: default, photo, picture, drawing, icon, text - -preset must come first, as it overwrites other parameters. + -preset must come first, as it overwrites other parameters + -m <int> ............... compression method (0=fast, 6=slowest) -segments <int> ........ number of segments to use (1..4) - -size <int> ............ Target size (in bytes) - -psnr <float> .......... Target PSNR (in dB. typically: 42) + -size <int> ............ target size (in bytes) + -psnr <float> .......... target PSNR (in dB. typically: 42) - -s <int> <int> ......... Input size (width x height) for YUV - -sns <int> ............. Spatial Noise Shaping (0:off, 100:max) + -s <int> <int> ......... input size (width x height) for YUV + -sns <int> ............. spatial noise shaping (0:off, 100:max) -f <int> ............... filter strength (0=off..100) -sharpness <int> ....... filter sharpness (0:most .. 7:least sharp) - -strong ................ use strong filter instead of simple (default). - -nostrong .............. use simple filter instead of strong. + -strong ................ use strong filter instead of simple (default) + -nostrong .............. use simple filter instead of strong -partition_limit <int> . limit quality to fit the 512k limit on the first partition (0=no degradation ... 100=full) -pass <int> ............ analysis pass number (1..10) @@ -169,41 +171,40 @@ options: -resize <w> <h> ........ resize picture (after any cropping) -mt .................... use multi-threading if available -low_memory ............ reduce memory usage (slower encoding) - -map <int> ............. print map of extra info. - -print_psnr ............ prints averaged PSNR distortion. - -print_ssim ............ prints averaged SSIM distortion. - -print_lsim ............ prints local-similarity distortion. - -d <file.pgm> .......... dump the compressed output (PGM file). - -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. - -blend_alpha <hex> ..... Blend colors against background color + -map <int> ............. print map of extra info + -print_psnr ............ prints averaged PSNR distortion + -print_ssim ............ prints averaged SSIM distortion + -print_lsim ............ prints local-similarity distortion + -d <file.pgm> .......... dump the compressed output (PGM file) + -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 + -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. - -hint <string> ......... Specify image characteristics hint. - One of: photo, picture or graph + green=0xe0 and blue=0xd0 + -noalpha ............... discard any transparency information + -lossless .............. encode image losslessly + -hint <string> ......... specify image characteristics hint, + one of: photo, picture or graph -metadata <string> ..... comma separated list of metadata to copy from the input to the output if present. Valid values: all, none (default), exif, icc, xmp -short ................. condense printed message - -quiet ................. don't print anything. - -version ............... print version number and exit. - -noasm ................. disable all assembly optimizations. + -quiet ................. don't print anything + -version ............... print version number and exit + -noasm ................. disable all assembly optimizations -v ..................... verbose, e.g. print encoding/decoding times -progress .............. report encoding progress Experimental Options: - -jpeg_like ............. Roughly match expected JPEG size. - -af .................... auto-adjust filter strength. + -jpeg_like ............. roughly match expected JPEG size + -af .................... auto-adjust filter strength -pre <int> ............. pre-processing filter - The main options you might want to try in order to further tune the visual quality are: -preset @@ -262,19 +263,19 @@ Use following options to convert into alternate image formats: -yuv ......... save the raw YUV samples in flat layout Other options are: - -version .... print version number and exit. - -nofancy ..... don't use the fancy YUV420 upscaler. - -nofilter .... disable in-loop filtering. - -nodither .... disable dithering. + -version .... print version number and exit + -nofancy ..... don't use the fancy YUV420 upscaler + -nofilter .... disable in-loop filtering + -nodither .... disable dithering -dither <d> .. dithering strength (in 0..100) -mt .......... use multi-threading -crop <x> <y> <w> <h> ... crop output with the given rectangle -scale <w> <h> .......... scale the output (*after* any cropping) - -alpha ....... only save the alpha plane. + -alpha ....... only save the alpha plane -incremental . use incremental decoding (useful for tests) - -h ....... this help message. + -h ....... this help message -v ....... verbose (e.g. print encoding/decoding times) - -noasm ....... disable all assembly optimizations. + -noasm ....... disable all assembly optimizations Visualization tool: =================== @@ -288,19 +289,19 @@ Usage: vwebp in_file [options] Decodes the WebP image file and visualize it using OpenGL Options are: - -version .... print version number and exit. - -noicc ....... don't use the icc profile if present. - -nofancy ..... don't use the fancy YUV420 upscaler. - -nofilter .... disable in-loop filtering. - -dither <int> dithering strength (0..100). Default=50. - -mt .......... use multi-threading. - -info ........ print info. - -h ....... this help message. + -version .... print version number and exit + -noicc ....... don't use the icc profile if present + -nofancy ..... don't use the fancy YUV420 upscaler + -nofilter .... disable in-loop filtering + -dither <int> dithering strength (0..100), default=50 + -mt .......... use multi-threading + -info ........ print info + -h ....... this help message Keyboard shortcuts: - 'c' ................ toggle use of color profile. - 'i' ................ overlay file information. - 'q' / 'Q' / ESC .... quit. + 'c' ................ toggle use of color profile + 'i' ................ overlay file information + 'q' / 'Q' / ESC .... quit Building: --------- @@ -336,24 +337,24 @@ vwebp. Usage: gif2webp [options] gif_file -o webp_file -options: +Options: -h / -help ............ this help - -lossy ................. Encode image using lossy compression. - -mixed ................. For each frame in the image, pick lossy - or lossless compression heuristically. + -lossy ................. encode image using lossy compression + -mixed ................. for each frame in the image, pick lossy + or lossless compression heuristically -q <float> ............. quality factor (0:small..100:big) -m <int> ............... compression method (0=fast, 6=slowest) - -kmin <int> ............ Min distance between key frames - -kmax <int> ............ Max distance between key frames + -kmin <int> ............ min distance between key frames + -kmax <int> ............ max distance between key frames -f <int> ............... filter strength (0=off..100) -metadata <string> ..... comma separated list of metadata to - copy from the input to the output if present. + copy from the input to the output if present Valid values: all, none, icc, xmp (default) -mt .................... use multi-threading if available - -version ............... print version number and exit. - -v ..................... verbose. - -quiet ................. don't print anything. + -version ............... print version number and exit + -v ..................... verbose + -quiet ................. don't print anything Building: --------- @@ -442,15 +443,20 @@ The encoding flow looks like: // Set up a byte-output write method. WebPMemoryWriter, for instance. WebPMemoryWriter wrt; + WebPMemoryWriterInit(&wrt); // initialize 'wrt' + pic.writer = MyFileWriter; pic.custom_ptr = my_opaque_structure_to_make_MyFileWriter_work; - // initialize 'wrt' here... // Compress! int ok = WebPEncode(&config, &pic); // ok = 0 => error occurred! WebPPictureFree(&pic); // must be called independently of the 'ok' result. // output data should have been handled by the writer at that point. + // -> compressed data is the memory buffer described by wrt.mem / wrt.size + + // deallocate the memory used by compressed data + WebPMemoryWriterClear(&wrt); -------------------------------------- END PSEUDO EXAMPLE |