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128 lines
4.8 KiB
Plaintext
128 lines
4.8 KiB
Plaintext
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DWEBP(1) DWEBP(1)
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NAME
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dwebp - decompress a WebP file to an image file
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SYNOPSIS
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dwebp [options] input_file.webp
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DESCRIPTION
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This manual page documents the dwebp command.
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dwebp decompresses WebP files into PNG, PAM, PPM or PGM images.
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OPTIONS
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The basic options are:
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-h Print usage summary.
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-version
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Print the version number (as major.minor.revision) and exit.
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-o string
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Specify the name of the output file (as PNG format by default).
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Using "-" as output name will direct output to 'stdout'.
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-- string
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Explicitly specify the input file. This option is useful if the
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input file starts with an '-' for instance. This option must
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appear last. Any other options afterward will be ignored. If
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the input file is "-", the data will be read from stdin instead
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of a file.
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-bmp Change the output format to uncompressed BMP.
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-tiff Change the output format to uncompressed TIFF.
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-pam Change the output format to PAM (retains alpha).
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-ppm Change the output format to PPM (discards alpha).
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-pgm Change the output format to PGM. The output consists of
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luma/chroma samples instead of RGB, using the IMC4 layout. This
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option is mainly for verification and debugging purposes.
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-yuv Change the output format to raw YUV. The output consists of
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luma/chroma-U/chroma-V samples instead of RGB, saved sequen‐
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tially as individual planes. This option is mainly for verifica‐
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tion and debugging purposes.
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-nofancy
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Don't use the fancy upscaler for YUV420. This may lead to jaggy
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edges (especially the red ones), but should be faster.
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-nofilter
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Don't use the in-loop filtering process even if it is required
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by the bitstream. This may produce visible blocks on the non-
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compliant output, but it will make the decoding faster.
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-dither strength
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Specify a dithering strength between 0 and 100. Dithering is a
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post-processing effect applied to chroma components in lossy
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compression. It helps by smoothing gradients and avoiding band‐
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ing artifacts.
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-nodither
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Disable all dithering (default).
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-mt Use multi-threading for decoding, if possible.
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-crop x_position y_position width height
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Crop the decoded picture to a rectangle with top-left corner at
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coordinates (x_position, y_position) and size width x height.
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This cropping area must be fully contained within the source
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rectangle. The top-left corner will be snapped to even coordi‐
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nates if needed. This option is meant to reduce the memory
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needed for cropping large images. Note: the cropping is applied
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before any scaling.
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-scale width height
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Rescale the decoded picture to dimension width x height. This
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option is mostly intended to reducing the memory needed to
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decode large images, when only a small version is needed (thumb‐
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nail, preview, etc.). Note: scaling is applied after cropping.
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-v Print extra information (decoding time in particular).
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-noasm Disable all assembly optimizations.
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BUGS
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Please report all bugs to our issue tracker:
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http://code.google.com/p/webp/issues
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Patches welcome! See this page to get started: http://www.webmpro‐
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ject.org/code/contribute/submitting-patches/
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EXAMPLES
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dwebp picture.webp -o output.png
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dwebp picture.webp -ppm -o output.ppm
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dwebp -o output.ppm -- ---picture.webp
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cat picture.webp | dwebp -o - -- - > output.ppm
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AUTHORS
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dwebp was written by the WebP team.
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The latest source tree is available at http://www.webmproject.org/code
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This manual page was written by Pascal Massimino <pascal.mas‐
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simino@gmail.com>, for the Debian project (and may be used by others).
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SEE ALSO
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cwebp(1), gif2webp(1), webpmux(1)
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Please refer to http://developers.google.com/speed/webp/ for additional
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information.
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Output file format details
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PAM: http://netpbm.sourceforge.net/doc/pam.html
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PGM: http://netpbm.sourceforge.net/doc/pgm.html
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PPM: http://netpbm.sourceforge.net/doc/ppm.html
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PNG: http://www.libpng.org/pub/png/png-sitemap.html#info
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July 22, 2014 DWEBP(1)
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