gif2webp.1 (6420B)
1 .\" Hey, EMACS: -*- nroff -*- 2 .TH GIF2WEBP 1 "November 4, 2024" 3 .SH NAME 4 gif2webp \- Convert a GIF image to WebP 5 .SH SYNOPSIS 6 .B gif2webp 7 .RI [ options ] " input_file.gif \-o output_file.webp 8 .br 9 .SH DESCRIPTION 10 This manual page documents the 11 .B gif2webp 12 command. 13 .PP 14 \fBgif2webp\fP converts a GIF image to a WebP image. 15 .SH OPTIONS 16 The basic options are: 17 .TP 18 .BI \-o " string 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'. 22 .TP 23 .BI \-\- " string 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. 28 .TP 29 .B \-h, \-help 30 Usage information. 31 .TP 32 .B \-version 33 Print the version number (as major.minor.revision) and exit. 34 .TP 35 .B \-lossy 36 Encode the image using lossy compression. 37 .TP 38 .B \-mixed 39 Mixed compression mode: optimize compression of the image by picking either 40 lossy or lossless compression for each frame heuristically. 41 .TP 42 .BI \-near_lossless " int 43 Specify the level of near\-lossless image preprocessing. This option adjusts 44 pixel values to help compressibility, but has minimal impact on the visual 45 quality. It triggers lossless compression mode automatically. The range is 0 46 (maximum preprocessing) to 100 (no preprocessing, the default). The typical 47 value is around 60. Note that lossy with \fB\-q 100\fP can at times yield 48 better results. 49 .TP 50 .B \-sharp_yuv 51 Use more accurate and sharper RGB->YUV conversion. Note that this process is 52 slower than the default 'fast' RGB->YUV conversion. 53 .TP 54 .BI \-q " float 55 Specify the compression factor for RGB channels between 0 and 100. The default 56 is 75. 57 .br 58 In case of lossless compression (default), a small factor enables faster 59 compression speed, but produces a larger file. Maximum compression is achieved 60 by using a value of 100. 61 .br 62 In case of lossy compression (specified by the \-lossy option), a small factor 63 produces a smaller file with lower quality. Best quality is achieved by using a 64 value of 100. 65 .TP 66 .BI \-m " int 67 Specify the compression method to use. This parameter controls the 68 trade off between encoding speed and the compressed file size and quality. 69 Possible values range from 0 to 6. Default value is 4. 70 When higher values are used, the encoder will spend more time inspecting 71 additional encoding possibilities and decide on the quality gain. 72 Lower value can result is faster processing time at the expense of 73 larger file size and lower compression quality. 74 .TP 75 .BI \-min_size 76 Encode image to achieve smallest size. This disables key frame insertion and 77 picks the dispose method resulting in the smallest output for each frame. It 78 uses lossless compression by default, but can be combined with \-q, \-m, 79 \-lossy or \-mixed options. 80 .TP 81 .BI \-kmin " int 82 .TP 83 .BI \-kmax " int 84 Specify the minimum and maximum distance between consecutive key frames 85 (independently decodable frames) in the output animation. The tool will insert 86 some key frames into the output animation as needed so that this criteria is 87 satisfied. 88 .br 89 A 'kmax' value of 0 will turn off insertion of key frames. A 'kmax' value of 1 90 will result in all frames being key frames. 'kmin' value is not taken into 91 account in both these special cases. 92 Typical values are in the range 3 to 30. Default values are kmin = 9, 93 kmax = 17 for lossless compression and kmin = 3, kmax = 5 for lossy compression. 94 .br 95 These two options are relevant only for animated images with large number of 96 frames (>50). 97 .br 98 When lower values are used, more frames will be converted to key frames. This 99 may lead to smaller number of frames required to decode a frame on average, 100 thereby improving the decoding performance. But this may lead to slightly bigger 101 file sizes. 102 Higher values may lead to worse decoding performance, but smaller file sizes. 103 .br 104 Some restrictions: 105 .br 106 (i) kmin < kmax, 107 .br 108 (ii) kmin >= kmax / 2 + 1 and 109 .br 110 (iii) kmax - kmin <= 30. 111 .br 112 If any of these restrictions are not met, they will be enforced automatically. 113 .TP 114 .BI \-metadata " string 115 A comma separated list of metadata to copy from the input to the output if 116 present. 117 Valid values: \fBall\fP, \fBnone\fP, \fBicc\fP, \fBxmp\fP. 118 The default is \fBxmp\fP. 119 .TP 120 .BI \-f " int 121 For lossy encoding only (specified by the \-lossy option). Specify the strength 122 of the deblocking filter, between 0 (no filtering) and 100 (maximum filtering). 123 A value of 0 will turn off any filtering. Higher value will increase the 124 strength of the filtering process applied after decoding the picture. The higher 125 the value the smoother the picture will appear. Typical values are usually in 126 the range of 20 to 50. 127 .TP 128 .B \-mt 129 Use multi-threading for encoding, if possible. 130 .TP 131 .B \-loop_compatibility 132 If enabled, handle the loop information in a compatible fashion for Chrome 133 version prior to M62 (inclusive) and Firefox. 134 .TP 135 .B \-v 136 Print extra information. 137 .TP 138 .B \-quiet 139 Do not print anything. 140 141 .SH EXIT STATUS 142 If there were no problems during execution, \fBgif2webp\fP exits with the value 143 of the C constant \fBEXIT_SUCCESS\fP. This is usually zero. 144 .PP 145 If an error occurs, \fBgif2webp\fP exits with the value of the C constant 146 \fBEXIT_FAILURE\fP. This is usually one. 147 148 .SH EXAMPLES 149 gif2webp picture.gif \-o picture.webp 150 .br 151 gif2webp \-q 70 picture.gif \-o picture.webp 152 .br 153 gif2webp \-lossy \-m 3 picture.gif \-o picture_lossy.webp 154 .br 155 gif2webp \-lossy \-f 50 picture.gif \-o picture.webp 156 .br 157 gif2webp \-q 70 \-o picture.webp \-\- \-\-\-picture.gif 158 .br 159 cat picture.gif | gif2webp \-o \- \-\- \- > output.webp 160 161 .SH AUTHORS 162 \fBgif2webp\fP is a part of libwebp and was written by the WebP team. 163 .br 164 The latest source tree is available at 165 https://chromium.googlesource.com/webm/libwebp 166 .PP 167 This manual page was written by Urvang Joshi <urvang@google.com>, for the 168 Debian project (and may be used by others). 169 170 .SH REPORTING BUGS 171 Please report all bugs to the issue tracker: 172 https://issues.webmproject.org 173 .br 174 Patches welcome! See this page to get started: 175 https://www.webmproject.org/code/contribute/submitting\-patches/ 176 177 .SH SEE ALSO 178 .BR cwebp (1), 179 .BR dwebp (1), 180 .BR webpmux (1) 181 .br 182 Please refer to https://developers.google.com/speed/webp/ for additional 183 information.