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Edit File: dwebp.1

.\" Hey, EMACS: -*- nroff -*- .TH DWEBP 1 "November 17, 2021" .SH NAME dwebp \- decompress a WebP file to an image file .SH SYNOPSIS .B dwebp .RI [ options ] " input_file.webp .br .SH DESCRIPTION This manual page documents the .B dwebp command. .PP \fBdwebp\fP decompresses WebP files into PNG, PAM, PPM or PGM images. Note: Animated WebP files are not supported. .SH OPTIONS The basic options are: .TP .B \-h Print usage summary. .TP .B \-version Print the version number (as major.minor.revision) and exit. .TP .BI \-o " string Specify the name of the output file (as PNG format by default). Using "-" as output name will direct output to 'stdout'. .TP .BI \-\- " string Explicitly specify the input file. This option is useful if the input file starts with an '\-' for instance. This option must appear \fBlast\fP. Any other options afterward will be ignored. If the input file is "\-", the data will be read from \fIstdin\fP instead of a file. .TP .B \-bmp Change the output format to uncompressed BMP. .TP .B \-tiff Change the output format to uncompressed TIFF. .TP .B \-pam Change the output format to PAM (retains alpha). .TP .B \-ppm Change the output format to PPM (discards alpha). .TP .B \-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. .TP .B \-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. .TP .B \-nofancy Don't use the fancy upscaler for YUV420. This may lead to jaggy edges (especially the red ones), but should be faster. .TP .B \-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. .TP .BI \-dither " strength Specify a dithering \fBstrength\fP 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. .TP .BI \-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. .TP .B \-nodither Disable all dithering (default). .TP .B \-mt Use multi-threading for decoding, if possible. .TP .BI \-crop " x_position y_position width height Crop the decoded picture to a rectangle with top-left corner at coordinates (\fBx_position\fP, \fBy_position\fP) and size \fBwidth\fP x \fBheight\fP. 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 \fIbefore\fP any scaling. .TP .B \-flip Flip decoded image vertically (can be useful for OpenGL textures for instance). .TP \fB\-resize\fR, \fB\-scale\fI width height\fR Rescale the decoded picture to dimension \fBwidth\fP x \fBheight\fP. 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 \fIafter\fP cropping. If either (but not both) of the \fBwidth\fP or \fBheight\fP parameters is 0, the value will be calculated preserving the aspect-ratio. .TP .B \-quiet Do not print anything. .TP .B \-v Print extra information (decoding time in particular). .TP .B \-noasm Disable all assembly optimizations. .SH BUGS Please report all bugs to the issue tracker: https://bugs.chromium.org/p/webp .br Patches welcome! See this page to get started: https://www.webmproject.org/code/contribute/submitting\-patches/ .SH EXAMPLES dwebp picture.webp \-o output.png .br dwebp picture.webp \-ppm \-o output.ppm .br dwebp \-o output.ppm \-\- \-\-\-picture.webp .br cat picture.webp | dwebp \-o \- \-\- \- > output.ppm .SH AUTHORS \fBdwebp\fP is a part of libwebp and was written by the WebP team. .br The latest source tree is available at https://chromium.googlesource.com/webm/libwebp .PP This manual page was written by Pascal Massimino <pascal.massimino@gmail.com>, for the Debian project (and may be used by others). .SH SEE ALSO .BR cwebp (1), .BR gif2webp (1), .BR webpmux (1) .br Please refer to https://developers.google.com/speed/webp/ for additional information. .SS Output file format details PAM: http://netpbm.sourceforge.net/doc/pam.html .br PGM: http://netpbm.sourceforge.net/doc/pgm.html .br PPM: http://netpbm.sourceforge.net/doc/ppm.html .br PNG: http://www.libpng.org/pub/png/png-sitemap.html#info