dwebp(1) - f32

1DWEBP(1)                    General Commands Manual                   DWEBP(1)
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NAME

6       dwebp - decompress a WebP file to an image file
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SYNOPSIS

9       dwebp [options] input_file.webp
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DESCRIPTION

12       This manual page documents the dwebp command.
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14       dwebp decompresses WebP files into PNG, PAM, PPM or PGM images.
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OPTIONS

17       The basic options are:
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19       -h     Print usage summary.
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21       -version
22              Print the version number (as major.minor.revision) and exit.
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24       -o string
25              Specify  the name of the output file (as PNG format by default).
26              Using "-" as output name will direct output to 'stdout'.
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28       -- string
29              Explicitly specify the input file. This option is useful if  the
30              input  file  starts  with  an '-' for instance. This option must
31              appear last.  Any other options afterward will  be  ignored.  If
32              the  input file is "-", the data will be read from stdin instead
33              of a file.
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35       -bmp   Change the output format to uncompressed BMP.
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37       -tiff  Change the output format to uncompressed TIFF.
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39       -pam   Change the output format to PAM (retains alpha).
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41       -ppm   Change the output format to PPM (discards alpha).
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43       -pgm   Change  the  output  format  to  PGM.  The  output  consists  of
44              luma/chroma  samples instead of RGB, using the IMC4 layout. This
45              option is mainly for verification and debugging purposes.
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47       -yuv   Change the output format to raw  YUV.  The  output  consists  of
48              luma/chroma-U/chroma-V  samples  instead  of  RGB, saved sequen‐
49              tially as individual planes. This option is mainly for verifica‐
50              tion and debugging purposes.
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52       -nofancy
53              Don't  use the fancy upscaler for YUV420. This may lead to jaggy
54              edges (especially the red ones), but should be faster.
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56       -nofilter
57              Don't use the in-loop filtering process even if it  is  required
58              by  the  bitstream.  This may produce visible blocks on the non-
59              compliant output, but it will make the decoding faster.
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61       -dither strength
62              Specify a dithering strength between 0 and 100. Dithering  is  a
63              post-processing  effect  applied  to  chroma components in lossy
64              compression.  It helps by smoothing gradients and avoiding band‐
65              ing artifacts.
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67       -alpha_dither
68              If  the  compressed  file contains a transparency plane that was
69              quantized during compression, this flag will allow dithering the
70              reconstructed  plane  in order to generate smoother transparency
71              gradients.
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73       -nodither
74              Disable all dithering (default).
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76       -mt    Use multi-threading for decoding, if possible.
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78       -crop x_position y_position width height
79              Crop the decoded picture to a rectangle with top-left corner  at
80              coordinates  (x_position,  y_position)  and size width x height.
81              This cropping area must be fully  contained  within  the  source
82              rectangle.   The top-left corner will be snapped to even coordi‐
83              nates if needed.  This option is  meant  to  reduce  the  memory
84              needed for cropping large images.  Note: the cropping is applied
85              before any scaling.
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87       -flip  Flip decoded image vertically (can be useful for OpenGL textures
88              for instance).
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90       -resize, -scale width height
91              Rescale  the  decoded  picture to dimension width x height. This
92              option is mostly intended  to  reducing  the  memory  needed  to
93              decode large images, when only a small version is needed (thumb‐
94              nail, preview, etc.). Note: scaling is applied  after  cropping.
95              If either (but not both) of the width or height parameters is 0,
96              the value will be calculated preserving the aspect-ratio.
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98       -quiet Do not print anything.
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100       -v     Print extra information (decoding time in particular).
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102       -noasm Disable all assembly optimizations.
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BUGS

106       Please    report     all     bugs     to     the     issue     tracker:
107       https://bugs.chromium.org/p/webp
108       Patches  welcome!  See  this  page  to get started: http://www.webmpro‐
109       ject.org/code/contribute/submitting-patches/
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EXAMPLES

113       dwebp picture.webp -o output.png
114       dwebp picture.webp -ppm -o output.ppm
115       dwebp -o output.ppm -- ---picture.webp
116       cat picture.webp | dwebp -o - -- - > output.ppm
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AUTHORS

120       dwebp is a part of libwebp and was written by the WebP team.
121       The  latest  source  tree  is  available  at   https://chromium.google‐
122       source.com/webm/libwebp
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124       This   manual   page  was  written  by  Pascal  Massimino  <pascal.mas‐
125       simino@gmail.com>, for the Debian project (and may be used by others).
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