# DWEBP

NAME
SYNOPSIS
DESCRIPTION
OPTIONS
BUGS
EXAMPLES
AUTHORS
SEE ALSO

## NAME

dwebp − decompress a WebP file to an image file

## SYNOPSIS

dwebp [options] input_file.webp

## DESCRIPTION

This manual page documents the dwebp command.

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 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.

−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.

| −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).

## SEE ALSO

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