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DWEBP(1)               DragonFly 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.  Note:
       Animated WebP files are not supported.


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.

       -alpha_dither
              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.

       -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:
       https://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 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 https://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

                               November 17, 2021                      DWEBP(1)

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