DWEBP(1)                                General Commands Manual                                DWEBP(1)

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 ig‐
              nored. 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 pur‐
              poses.

       -yuv   Change the output format to raw YUV. The output consists of  luma/chroma-U/chroma-V  sam‐
              ples  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 ap‐
              plied  to  chroma  components  in lossy compression.  It helps by smoothing gradients and
              avoiding banding artifacts.

       -alpha_dither
              If the compressed file contains a transparency plane that was quantized  during  compres‐
              sion,  this  flag  will  allow  dithering  the  reconstructed  plane in order to generate
              smoother transparency gradients.

       -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.

       -flip  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.

       -quiet Do not print anything.

       -v     Print extra information (decoding time in particular).

       -noasm Disable all assembly optimizations.

BUGS
       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/sub‐
       mitting-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 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).

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

                                             June 23, 2016                                     DWEBP(1)

Usage: dwebp in_file [options] [-o out_file]

Decodes the WebP image file to PNG format [Default]
Use following options to convert into alternate image formats:
  -pam ......... save the raw RGBA samples as a color PAM
  -ppm ......... save the raw RGB samples as a color PPM
  -bmp ......... save as uncompressed BMP format
  -tiff ........ save as uncompressed TIFF format
  -pgm ......... save the raw YUV samples as a grayscale PGM
                 file with IMC4 layout
  -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
  -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
  -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