1 .\" Hey, EMACS: -*- nroff -*-
2 .TH GIF2WEBP 1 "May 1, 2020"
4 gif2webp \- Convert a GIF image to WebP
7 .RI [ options ] " input_file.gif \-o output_file.webp
10 This manual page documents the
14 \fBgif2webp\fP converts a GIF image to a WebP image.
16 The basic options are:
19 Specify the name of the output WebP file. If omitted, \fBgif2webp\fP will
20 perform conversion but only report statistics.
21 Using "\-" as output name will direct output to 'stdout'.
24 Explicitly specify the input file. This option is useful if the input
25 file starts with an '\-' for instance. This option must appear \fBlast\fP.
26 Any other options afterward will be ignored. If the input file is "\-",
27 the data will be read from \fIstdin\fP instead of a file.
33 Print the version number (as major.minor.revision) and exit.
36 Encode the image using lossy compression.
39 Mixed compression mode: optimize compression of the image by picking either
40 lossy or lossless compression for each frame heuristically.
43 Specify the compression factor for RGB channels between 0 and 100. The default
46 In case of lossless compression (default), a small factor enables faster
47 compression speed, but produces a larger file. Maximum compression is achieved
48 by using a value of 100.
50 In case of lossy compression (specified by the \-lossy option), a small factor
51 produces a smaller file with lower quality. Best quality is achieved by using a
55 Specify the compression method to use. This parameter controls the
56 trade off between encoding speed and the compressed file size and quality.
57 Possible values range from 0 to 6. Default value is 4.
58 When higher values are used, the encoder will spend more time inspecting
59 additional encoding possibilities and decide on the quality gain.
60 Lower value can result is faster processing time at the expense of
61 larger file size and lower compression quality.
64 Encode image to achieve smallest size. This disables key frame insertion and
65 picks the dispose method resulting in the smallest output for each frame. It
66 uses lossless compression by default, but can be combined with \-q, \-m,
67 \-lossy or \-mixed options.
72 Specify the minimum and maximum distance between consecutive key frames
73 (independently decodable frames) in the output animation. The tool will insert
74 some key frames into the output animation as needed so that this criteria is
77 A 'kmax' value of 0 will turn off insertion of key frames. A 'kmax' value of 1
78 will result in all frames being key frames. 'kmin' value is not taken into
79 account in both these special cases.
80 Typical values are in the range 3 to 30. Default values are kmin = 9,
81 kmax = 17 for lossless compression and kmin = 3, kmax = 5 for lossy compression.
83 These two options are relevant only for animated images with large number of
86 When lower values are used, more frames will be converted to key frames. This
87 may lead to smaller number of frames required to decode a frame on average,
88 thereby improving the decoding performance. But this may lead to slightly bigger
90 Higher values may lead to worse decoding performance, but smaller file sizes.
96 (ii) kmin >= kmax / 2 + 1 and
98 (iii) kmax - kmin <= 30.
100 If any of these restrictions are not met, they will be enforced automatically.
102 .BI \-metadata " string
103 A comma separated list of metadata to copy from the input to the output if
105 Valid values: \fBall\fP, \fBnone\fP, \fBicc\fP, \fBxmp\fP.
106 The default is \fBxmp\fP.
109 For lossy encoding only (specified by the \-lossy option). Specify the strength
110 of the deblocking filter, between 0 (no filtering) and 100 (maximum filtering).
111 A value of 0 will turn off any filtering. Higher value will increase the
112 strength of the filtering process applied after decoding the picture. The higher
113 the value the smoother the picture will appear. Typical values are usually in
114 the range of 20 to 50.
117 Use multi-threading for encoding, if possible.
119 .B \-loop_compatibility
120 If enabled, handle the loop information in a compatible fashion for Chrome
121 version prior to M62 (inclusive) and Firefox.
124 Print extra information.
127 Do not print anything.
130 Please report all bugs to the issue tracker:
131 https://bugs.chromium.org/p/webp
133 Patches welcome! See this page to get started:
134 http://www.webmproject.org/code/contribute/submitting-patches/
137 gif2webp picture.gif \-o picture.webp
139 gif2webp \-q 70 picture.gif \-o picture.webp
141 gif2webp \-lossy \-m 3 picture.gif \-o picture_lossy.webp
143 gif2webp \-lossy \-f 50 picture.gif \-o picture.webp
145 gif2webp \-q 70 \-o picture.webp \-\- \-\-\-picture.gif
147 cat picture.gif | gif2webp \-o \- \-\- \- > output.webp
150 \fBgif2webp\fP is a part of libwebp and was written by the WebP team.
152 The latest source tree is available at
153 https://chromium.googlesource.com/webm/libwebp
155 This manual page was written by Urvang Joshi <urvang@google.com>, for the
156 Debian project (and may be used by others).
163 Please refer to http://developers.google.com/speed/webp/ for additional