dwebp(1) - f35

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.  Note:
15       Animated WebP files are not supported.
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OPTIONS

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

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

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

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