Section: User Commands (1)
Updated: June 23, 2016
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dwebp - decompress a WebP file to an image file  


dwebp [options] input_file.webp


This manual page documents the dwebp command.

dwebp decompresses WebP files into PNG, PAM, PPM or PGM images.  


The basic options are:
Print usage summary.
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.
Change the output format to uncompressed BMP.
Change the output format to uncompressed TIFF.
Change the output format to PAM (retains alpha).
Change the output format to PPM (discards alpha).
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.
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.
Don't use the fancy upscaler for YUV420. This may lead to jaggy edges (especially the red ones), but should be faster.
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.
If the compressed file contains a transparency plane that was quantized during compression, this flag will allow dithering the reconstructed plane in order to generate smoother transparency gradients.
Disable all dithering (default).
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 size width x height. 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 decoded image vertically (can be useful for OpenGL textures for instance).
-resize, -scale width height
Rescale the decoded picture to dimension width x height. 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. If either (but not both) of the width or height parameters is 0, the value will be calculated preserving the aspect-ratio.
Do not print anything.
Print extra information (decoding time in particular).
Disable all assembly optimizations.



Please report all bugs to the issue tracker: https://bugs.chromium.org/p/webp
Patches welcome! See this page to get started: http://www.webmproject.org/code/contribute/submitting-patches/



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



dwebp is a part of libwebp and was written by the WebP team.
The latest source tree is available at https://chromium.googlesource.com/webm/libwebp

This manual page was written by Pascal Massimino <pascal.massimino@gmail.com>, for the Debian project (and may be used by others).



cwebp(1), gif2webp(1), webpmux(1)
Please refer to http://developers.google.com/speed/webp/ for additional information.  

Output file format details

PAM: http://netpbm.sourceforge.net/doc/pam.html
PGM: http://netpbm.sourceforge.net/doc/pgm.html
PPM: http://netpbm.sourceforge.net/doc/ppm.html
PNG: http://www.libpng.org/pub/png/png-sitemap.html#info



Output file format details