GIF

GIF (CompuServe, 1987) is an indexed-colour format with LZW compression: at most 256 colours per frame, one fully transparent colour at most, no partial alpha. It survives because every chat app, forum and browser plays it without asking. Compression is poor by modern standards, so GIFs of video-like content are many times larger than the same clip as video, animated WebP, animated AVIF or APNG.

Property	Value
Compression	Lossless LZW of palette indices (making the palette is the lossy step)
Colours	256 per frame (a global table plus optional per-frame tables)
Transparency	One fully transparent palette index, no partial alpha
Animation	Yes, frame delays in hundredths of a second, loop count
Royalty-free	Yes

When to use it

• Short loops that must work in apps that accept nothing else: chat, forums, issue trackers, email.
• Small flat-colour animations, pixel art and UI demos with few colours and little motion.
• Don’t use it for screen recordings or clips of film or games if you control the page. A muted, looping <video> (MP4 or WebM) is far smaller and keeps full colour. Animated WebP or AVIF is the middle path when you need an <img>.

Make a GIF with FFmpeg

Converting straight to GIF makes FFmpeg use a generic palette, which looks dithered and muddy. Generate a palette from the clip and apply it. In one command:

ffmpeg -i input.mp4 -vf "fps=15,scale=480:-1:flags=lanczos,split[a][b];[a]palettegen[p];[b][p]paletteuse" output.gif

or in two steps, which lets you reuse or inspect the palette:

ffmpeg -i input.mp4 -vf "fps=15,scale=480:-1:flags=lanczos,palettegen" palette.png
ffmpeg -i input.mp4 -i palette.png -lavfi "fps=15,scale=480:-1:flags=lanczos[x];[x][1:v]paletteuse" output.gif

Frame rate and width have the biggest effect on size. Use a trim (-ss and -t) to keep clips short.

Option	Use
palettegen=stats_mode=diff	Weights colours towards the parts of the image that change. Better when the background is static (screen recordings).
palettegen=stats_mode=single with paletteuse=new=1	One palette per frame. Helps when colours change a lot between scenes, but frames carry their own palettes and the file usually grows.
paletteuse=dither=bayer:bayer_scale=5	Ordered dithering gives much smaller files and no shimmering noise, at the cost of a visible crosshatch pattern. Default is sierra2_4a, which looks smoother but compresses worse.
paletteuse=diff_mode=rectangle	Only re-encodes the changed rectangle of each frame. Helps whenever part of the picture is static.
palettegen=max_colors=128	Fewer colours, smaller file.
-loop	0 loops forever (the default), -1 plays once.

Frame delays are stored in centiseconds, so 15 fps (6.67 cs) is approximated, and browsers play delays of 1 cs or less as 10 cs, so 50 fps is the ceiling. 25 fps (4 cs) and 20 fps (5 cs) are exact.

gifski

gifski (AGPL-3.0) produces much better-looking GIFs than FFmpeg’s filters by using per-frame palettes with temporal dithering, so frames can use thousands of colours across a clip.

ffmpeg -i input.mp4 -f yuv4mpegpipe - | gifski --fps 15 --width 640 -o output.gif -
gifski --quality 80 --width 640 --fps 15 -o output.gif frame*.png

gifski limits animations to about 800×600 unless you pass --width. --fps defaults to 20: video input (Y4M) is resampled to that rate by dropping or duplicating frames, so set it in gifski rather than with an FFmpeg fps filter; for PNG frames it sets the playback speed. To shrink the output, reduce --width first (the biggest effect), then --quality (default 90), --lossy-quality and --motion-quality. If the source was lossy video, downscale it too: compression noise inflates the file.

Optimise an existing GIF with Gifsicle

gifsicle -O3 input.gif -o output.gif
gifsicle -O3 --lossy=80 --colors 128 input.gif -o output.gif

-O3 is lossless frame-rectangle optimisation. --lossy (bare = 20) trades noise for size, and --colors re-quantises the palette. Use gifsicle --info to inspect frames, delays and disposal. Quote frame selectors such as '#0' so the shell doesn’t read them as comments.

Pitfalls

• Palette per scene: a single global palette over a clip with different scenes looks bad; use stats_mode=single or split the clip.
• Transparency has no soft edges: antialiased cut-outs get a halo against backgrounds other than the one they were made on. Use paletteuse=alpha_threshold=... and test on light and dark backgrounds, or use APNG/WebP.
• Resizing after palette creation adds colours that don’t exist in the palette. Scale before palettegen, as in the commands above.
• Services that convert GIFs to video anyway: if the service accepts a video, upload that instead.

Full option reference

Every option and default for Gifsicle 1.96 and the FFmpeg 9.0.2 GIF encoder, muxer and palette filters. Reading option tables explains the Default column.

Complete Gifsicle parameter reference

Most frame options apply to the inputs that follow them, so order matters. A default is the state when the option is omitted; --same-... resets an earlier override. Bare --lossy means 20, bare --optimize means level 1 and bare --threads means 8.

All Gifsicle options, aliases and omission defaults

Parameter / aliases	Default	Values / effect
--append	not invoked	Appends frames from the following GIFs to the end of the input.
--app-extension, -x	not invoked	Adds an application extension (name, data) to the next frames.
--no-app-extensions	off	Removes application extensions from the input.
--background, -B, +B, --no-background, --bg, --no-bg	input-dependent	Sets the background colour, as a palette index or colour; the negated form picks index 0.
--batch, -b	off	Modifies the named input files in place; overwrites every input.
--careful, --no-careful	off	Writes larger GIFs that avoid bugs in some other programs.
--change-color, --no-change-color	none	Replaces one colour with another throughout: —change-color COL1 COL2.
--color-info, --cinfo, --no-cinfo, --no-color-info	off	Adds palette details to —info output.
--crop, --clip, --no-clip, --no-crop	none	Crops frames to X,Y+WxH or X,Y-X2,Y2.
--colors, -k, +k, --no-colors	0 (no reduction)	Reduces the palette to N colours (2–256); changes pixels.
--color-method, --method	diversity	Palette selection used by —colors: diversity, blend-diversity or median-cut.
--comment, -c	none added	Adds a comment before the next frame.
--no-comments, +c	off	Removes comments from the input; +c is the same.
--conserve-memory, --no-conserve-memory	0 (not requested)	Uses less memory at the cost of speed.
--crop-transparency, --no-crop-transparency	off	Crops transparent borders off the image.
--delay, -d, +d, --no-delay	input-dependent (-1)	Frame delay in hundredths of a second (16-bit).
--delete	not invoked	Deletes the selected frames until —done.
--disposal, -D, +D, --no-disposal	input-dependent (-1)	Frame disposal: none/0, asis/1, background/2, previous/3; 4–7 are reserved.
--dither, -f, +f, --no-dither	none	Dithers after a palette change; optional method name (see below), bare means default.
--done	not invoked	Ends a —delete, —insert-before, —append or —replace operation.
--explode, -e	off	Writes each frame to its own file, named input.frame-number.
--explode-by-name, -E	off	Like —explode, but names files after the stored frame names.
--extension	not invoked	Adds a raw extension: —extension NUMBER DATA.
--no-extension, --no-extensions, +x	off	Removes non-application extensions from the input; +x is the same.
--extension-info, --no-extension-info, --xinfo, --no-xinfo	off	Adds extension details to —info output.
--flip-horizontal, --no-flip-horizontal	off	Mirrors the following frames left to right.
--flip-vertical, --no-flip-vertical	off	Mirrors the following frames top to bottom.
--no-flip	not invoked	Clears pending flips.
--gamma, --no-gamma	sRGB	Gamma for colour reduction: sRGB, a number, or oklab on builds that support them.
--gray	off	Reduces to a grayscale palette; same as —use-colormap gray.
--help, -h	not invoked	Prints help and exits.
--ignore-errors, --no-ignore-errors	on	Keeps going after recoverable input errors; —no-ignore-errors quits on badly damaged GIFs.
--info, -I, +I, --no-info	off	Prints input information and suppresses GIF output; -II keeps the output.
--insert-before	not invoked	Inserts the following GIFs before the selected frame.
--interlace, -i, +i, --no-interlace	input-dependent (-1)	Writes interlaced frames; +i turns it off.
--logical-screen, -S, +S, --no-logical-screen, --screen, --no-screen	input-dependent	Canvas size WxH; the negated form recomputes it from the frames.
--loopcount, -l, +l, --no-loopcount	input-dependent (-2)	Repeats after the first play: =1 shows the animation twice; bare or forever loops endlessly.
--lossy	0	Trades colour accuracy for smaller files, adding noise; bare means 20.
--merge, -m	on (normal mode)	Combines all inputs into one GIF; this is the default mode.
--multifile, --no-multifile	off	Reads concatenated GIF streams from one file.
--name, -n	none added	Sets the next frame’s name.
--nextfile, --no-nextfile	off	Reads concatenated GIF streams, one stream per input.
--no-names, +n	off	Removes frame names from the input; +n is the same.
--optimize, -O, +O, --no-optimize	0	Shrinks animations: 1 stores changed areas, 2 adds transparency, 3 tries more methods; bare means 1.
--output, -o	mode-dependent	Output file; - means stdout.
--position, -p, +p, --no-position	input-dependent (-1,-1)	Frame offset as X,Y; the negated form sets 0,0.
--replace	not invoked	Replaces the selected frames with the following GIFs.
--resize, --no-resize, --resiz, --no-resiz, --resi, --no-resi, --res, --no-res	none	Resizes to WxH; 0 for one side keeps the aspect ratio, both sides can change it.
--resize-width, --no-resize-width	none	Resizes to this width, keeping the aspect ratio.
--resize-height, --no-resize-height	none	Resizes to this height, keeping the aspect ratio.
--resize-fit, --no-resize-fit, --resize-fi, --no-resize-fi, --resize-f, --no-resize-f	none	Shrinks to fit inside WxH, keeping the aspect ratio; never enlarges.
--resize-fit-width, --no-resize-fit-width	none	Shrinks to this width if wider, keeping the aspect ratio.
--resize-fit-height, --no-resize-fit-height	none	Shrinks to this height if taller, keeping the aspect ratio.
--resize-touch, --no-resize-touch, --resize-touc, --no-resize-touc, --resize-tou, --no-resize-tou, --resize-to, --no-resize-to, --resize-t, --no-resize-t	none	Resizes up or down until it touches WxH, keeping the aspect ratio.
--resize-touch-width, --no-resize-touch-width	none	Resizes to this width, enlarging if needed, keeping the aspect ratio.
--resize-touch-height, --no-resize-touch-height	none	Registered, but 1.96 treats the value as a width; use —resize-touch WxH.
--resize-geometry, --no-resize-geometry	none	Resizes using a geometry string with optional fit, fill and percentage modifiers.
--resize-method, --scale-method	mix	Resampling filter: point, mix, box, catrom, lanczos2, lanczos3 or mitchell.
--resize-colors, --no-resize-colors, --scale-colors, --no-scale-colors	0	Lets resizing add colours up to N (at most 256).
--rotate-90	off	Rotates the following frames by 90 degrees.
--rotate-180	off	Rotates the following frames 180 degrees.
--rotate-270	off	Rotates the following frames by 270 degrees.
--no-rotate	not invoked	Clears the pending rotation.
--same-app-extensions	not invoked	Goes back to the source’s application extensions.
--same-background, --same-bg	not invoked	Goes back to the source’s background colour.
--same-clip, --same-crop	not invoked	Goes back to the source’s frame size, with no crop.
--same-comments	not invoked	Goes back to the source’s comments.
--same-extensions	not invoked	Goes back to the source’s extensions.
--same-interlace	not invoked	Goes back to the source’s interlacing.
--same-logical-screen, --same-screen	not invoked	Goes back to the source’s canvas size.
--same-loopcount	not invoked	Goes back to the source’s loop count.
--same-disposal	not invoked	Goes back to the source’s frame disposal.
--same-delay	not invoked	Goes back to the source’s frame delays.
--same-names	not invoked	Goes back to the source’s frame names.
--same-position	not invoked	Goes back to the source’s frame positions.
--same-transparent	not invoked	Goes back to the source’s transparent colour.
--scale, --no-scale	none	Scales by X or XxY factors.
--size-info, --sinfo, --no-sinfo, --no-size-info	off	Adds compression details to —info output.
--transform-colormap, --no-transform-colormap	none	Pipes each output palette through a shell command; never insert untrusted text.
--transparent, -t, +t, --no-transparent	input-dependent	Makes a colour transparent, by palette index or colour; the negated form removes transparency.
--unoptimize, -U, +U, --no-unoptimize	off	Expands optimized frames into full images before editing.
--use-colormap, --no-use-colormap	none	Uses web, gray, bw or a GIF file’s palette; output may use only part of it.
--use-exact-colormap, --no-use-exact-colormap	none	Same palette sources, but keeps the whole palette.
--verbose, -V, +V, --no-verbose, -v, +v	off	Prints progress, listing files read and written.
--version	not invoked	Prints the version and exits.
--warnings, -w, +w, --no-warnings	on	-w hides warnings, +w shows them.
--threads, -j, +j, --no-threads	0	Uses N threads (bare means 8); needs a build with thread support.
FILE	stdin when no files are named	Input GIF; reads stdin when none is named.
FRAME	all input frames	Frame selector: #num, #first-last, #first- or #name; quote it so the shell keeps the #.
--	not invoked	Ends options so later arguments are filenames.

Dither names: none/posterize, default, floyd-steinberg/fs, atkinson/at, o3, o4, o8, ro64/ordered, diag45, halftone, sqhalftone. Comma-separated numbers select matrix size or level count (for example o,3).

--resize-touch-height is registered but dispatches its value as a width in 1.96, so use --resize-touch WxH. The initial gamma mode is sRGB although the help prints [2.2].

Complete FFmpeg GIF encoder options

Parameter / aliases	Default	Values / effect
-gifflags	offsetting+transdiff	offsetting (1) crops each frame to the changed area; transdiff (2) makes unchanged pixels transparent.
-gifimage	false	Writes each frame as its own complete single-image GIF.
-global_palette	true	Writes a global palette in the header when the frames allow it.

Complete FFmpeg GIF muxer options

Loop counts and the last frame’s delay change presentation, not decoded colours.

Parameter / aliases	Default	Values / effect
-loop	0	Loop count, -1 to 65535: 0 loops forever, -1 omits the loop extension.
-final_delay	-1	Hold time after the last frame in hundredths of a second; -1 uses that frame’s own duration.

Complete palettegen filter options

Filter syntax is palettegen=key=value:key=value.

Parameter / aliases	Default	Values / effect
max_colors	256	Palette size limit, 2–256; reserve_transparent uses one of the slots.
reserve_transparent	true	Reserves a palette entry for transparency; set 0 for opaque sources to gain a colour.
transparency_color	lime	Colour stored in the reserved transparent entry.
stats_mode	full	full (0) analyzes every frame, diff (1) only changed regions, single (2) builds one palette per frame.

Complete paletteuse filter options

debug_kdtree is a debugging option outside the stable filter API.

Parameter / aliases	Default	Values / effect
dither	sierra2_4a	Dither algorithm by name or number: 0 off, 1 bayer, 2 heckbert, 3 floyd_steinberg, 4 sierra2, 5 sierra2_4a, 6 sierra3, 7 burkes, 8 atkinson.
bayer_scale	2	0–5 for dither=bayer: lower shows more crosshatch, higher shows more banding.
diff_mode	0	rectangle (1) re-maps only the area that changed since the last frame; 0 maps whole frames.
new	false	Takes a new palette for every frame; pair with palettegen stats_mode=single.
alpha_threshold	128	Pixels with alpha below this value, 0–255, become transparent.
debug_kdtree	unset	Writes a Graphviz kd-tree dump to this path; for debugging only.