gif2webp.1
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.\" Hey, EMACS: -*- nroff -*- .TH GIF2WEBP 1 "November 4, 2024" .SH NAME gif2webp \- Convert a GIF image to WebP .SH SYNOPSIS .B gif2webp .RI [ options ] " input_file.gif \-o output_file.webp .br .SH DESCRIPTION This manual page documents the .B gif2webp command. .PP \fBgif2webp\fP converts a GIF image to a WebP image. .SH OPTIONS The basic options are: .TP .BI \-o " string Specify the name of the output WebP file. If omitted, \fBgif2webp\fP will perform conversion but only report statistics. 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 \-h, \-help Usage information. .TP .B \-version Print the version number (as major.minor.revision) and exit. .TP .B \-lossy Encode the image using lossy compression. .TP .B \-mixed Mixed compression mode: optimize compression of the image by picking either lossy or lossless compression for each frame heuristically. .TP .BI \-near_lossless " int Specify the level of near\-lossless image preprocessing. This option adjusts pixel values to help compressibility, but has minimal impact on the visual quality. It triggers lossless compression mode automatically. The range is 0 (maximum preprocessing) to 100 (no preprocessing, the default). The typical value is around 60. Note that lossy with \fB\-q 100\fP can at times yield better results. .TP .B \-sharp_yuv Use more accurate and sharper RGB->YUV conversion. Note that this process is slower than the default 'fast' RGB->YUV conversion. .TP .BI \-q " float Specify the compression factor for RGB channels between 0 and 100. The default is 75. .br In case of lossless compression (default), a small factor enables faster compression speed, but produces a larger file. Maximum compression is achieved by using a value of 100. .br In case of lossy compression (specified by the \-lossy option), a small factor produces a smaller file with lower quality. Best quality is achieved by using a value of 100. .TP .BI \-m " int Specify the compression method to use. This parameter controls the trade off between encoding speed and the compressed file size and quality. Possible values range from 0 to 6. Default value is 4. When higher values are used, the encoder will spend more time inspecting additional encoding possibilities and decide on the quality gain. Lower value can result is faster processing time at the expense of larger file size and lower compression quality. .TP .BI \-min_size Encode image to achieve smallest size. This disables key frame insertion and picks the dispose method resulting in the smallest output for each frame. It uses lossless compression by default, but can be combined with \-q, \-m, \-lossy or \-mixed options. .TP .BI \-kmin " int .TP .BI \-kmax " int Specify the minimum and maximum distance between consecutive key frames (independently decodable frames) in the output animation. The tool will insert some key frames into the output animation as needed so that this criteria is satisfied. .br A 'kmax' value of 0 will turn off insertion of key frames. A 'kmax' value of 1 will result in all frames being key frames. 'kmin' value is not taken into account in both these special cases. Typical values are in the range 3 to 30. Default values are kmin = 9, kmax = 17 for lossless compression and kmin = 3, kmax = 5 for lossy compression. .br These two options are relevant only for animated images with large number of frames (>50). .br When lower values are used, more frames will be converted to key frames. This may lead to smaller number of frames required to decode a frame on average, thereby improving the decoding performance. But this may lead to slightly bigger file sizes. Higher values may lead to worse decoding performance, but smaller file sizes. .br Some restrictions: .br (i) kmin < kmax, .br (ii) kmin >= kmax / 2 + 1 and .br (iii) kmax - kmin <= 30. .br If any of these restrictions are not met, they will be enforced automatically. .TP .BI \-metadata " string A comma separated list of metadata to copy from the input to the output if present. Valid values: \fBall\fP, \fBnone\fP, \fBicc\fP, \fBxmp\fP. The default is \fBxmp\fP. .TP .BI \-f " int For lossy encoding only (specified by the \-lossy option). Specify the strength of the deblocking filter, between 0 (no filtering) and 100 (maximum filtering). A value of 0 will turn off any filtering. Higher value will increase the strength of the filtering process applied after decoding the picture. The higher the value the smoother the picture will appear. Typical values are usually in the range of 20 to 50. .TP .B \-mt Use multi-threading for encoding, if possible. .TP .B \-loop_compatibility If enabled, handle the loop information in a compatible fashion for Chrome version prior to M62 (inclusive) and Firefox. .TP .B \-v Print extra information. .TP .B \-quiet Do not print anything. .SH EXIT STATUS If there were no problems during execution, \fBgif2webp\fP exits with the value of the C constant \fBEXIT_SUCCESS\fP. This is usually zero. .PP If an error occurs, \fBgif2webp\fP exits with the value of the C constant \fBEXIT_FAILURE\fP. This is usually one. .SH EXAMPLES gif2webp picture.gif \-o picture.webp .br gif2webp \-q 70 picture.gif \-o picture.webp .br gif2webp \-lossy \-m 3 picture.gif \-o picture_lossy.webp .br gif2webp \-lossy \-f 50 picture.gif \-o picture.webp .br gif2webp \-q 70 \-o picture.webp \-\- \-\-\-picture.gif .br cat picture.gif | gif2webp \-o \- \-\- \- > output.webp .SH AUTHORS \fBgif2webp\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 Urvang Joshi <urvang@google.com>, for the Debian project (and may be used by others). .SH REPORTING BUGS Please report all bugs to the issue tracker: https://issues.webmproject.org .br Patches welcome! See this page to get started: https://www.webmproject.org/code/contribute/submitting\-patches/ .SH SEE ALSO .BR cwebp (1), .BR dwebp (1), .BR webpmux (1) .br Please refer to https://developers.google.com/speed/webp/ for additional information.
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