Name
dwebp -- Decompress a WebP file to an image file
Synopsis
dwebp [options] input_file.webp
Description
dwebp decompresses WebP files into PNG, PAM, PPM or PGM images.
Options
The basic options are:
-h-
Print usage summary.
-version-
Print the version number (as major.minor.revision) and exit.
-o string-
Specify the name of the output file (as PNG format by default). Using "-" as output name will direct output to 'stdout'.
-- string-
Explicitly specify the input file. This option is useful if the input file starts with an '-' for instance. This option must appear
last. Any other options afterward will be ignored. If the input file is "-", the data will be read from stdin instead of a file. -bmp-
Change the output format to uncompressed BMP.
-tiff-
Change the output format to uncompressed TIFF.
-pam-
Change the output format to PAM (retains alpha).
-ppm-
Change the output format to PPM (discards alpha).
-pgm-
Change the output format to PGM. The output consists of luma/chroma samples instead of RGB, using the IMC4 layout. This option is mainly for verification and debugging purposes.
-yuv-
Change the output format to raw YUV. The output consists of luma/chroma-U/chroma-V samples instead of RGB, saved sequentially as individual planes. This option is mainly for verification and debugging purposes.
-nofancy-
Don't use the fancy upscaler for YUV420. This may lead to jaggy edges (especially the red ones), but should be faster.
-nofilter-
Don't use the in-loop filtering process even if it is required by the bitstream. This may produce visible blocks on the non-compliant output, but it will make the decoding faster.
-dither strength-
Specify a dithering strength between 0 and 100. Dithering is a post-processing effect applied to chroma components in lossy compression. It helps by smoothing gradients and avoiding banding artifacts.
-nodither-
Disable all dithering (default).
-mt-
Use multi-threading for decoding, if possible.
-crop x_position y_position width height-
Crop the decoded picture to a rectangle with top-left corner at coordinates (
x_position,y_position) and sizewidthxheight. This cropping area must be fully contained within the source rectangle. The top-left corner will be snapped to even coordinates if needed. This option is meant to reduce the memory needed for cropping large images. Note: the cropping is applied before any scaling. -flip-
Flip decoded image vertically (can be useful for OpenGL textures for instance).
-scale width height-
Rescale the decoded picture to dimension
widthxheight. This option is mostly intended to reducing the memory needed to decode large images, when only a small version is needed (thumbnail, preview, etc.). Note: scaling is applied after cropping. -v-
Print extra information (decoding time in particular).
-noasm-
Disable all assembly optimizations.
Bugs
-
Please report all bugs to our issue tracker: http://code.google.com/p/webp/issues
-
Patches welcome! See this page to get started: http://www.webmproject.org/code/contribute/submitting-patches/
Examples
dwebp picture.webp -o output.png
dwebp picture.webp -ppm -o output.ppm
dwebp -o output.ppm -- ---picture.webp
cat picture.webp | dwebp -o - -- - > output.ppm
Authors
dwebp was written by the WebP team. The latest source tree is available at
http://www.webmproject.org/code
This manual page was written by Pascal Massimino pascal.massimino@gmail.com, for the Debian project (and may be used by others).
Output file format details