A GIF has 256 colours, which anime art cannot spare
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diagramAn anime wallpaper saved as a GIF is limited to 256 colors, and anime art is close to the worst possible material for that limit, because it is built out of large areas of flat and near flat color that a small palette cannot represent without visible steps.
The format is not badly made, it is old, and it was designed for images with few colors and hard edges. What it does to a cel shaded sky, a gradient behind a character, or skin rendered in three tones is not a compression artifact you can tune away. It is the palette running out.
Why 256 colors ruins this art in particular
A GIF stores a palette of at most 256 entries and indexes every pixel into it, so an image containing more distinct colors than that has to lose some. Photographs survive this better than people expect, because their detail is noisy and the eye forgives a scattered approximation. Anime art does the opposite: it is composed of broad flat fields, and a flat field rendered with too few colors breaks into visible bands, which are steps of tone where a smooth transition should be.
Banding has a second cause worth separating from the palette, because the two compound. Ordinary 8-bit color has 256 levels per channel, and a large soft sky can cross fewer of those levels than it has pixels of width, so the steps become wide enough to see before any format is chosen. Give an image already at that edge a 256 color total palette and the two effects stack.
Dithering is the standard mitigation, and it trades one problem for another. It scatters pixels between two palette entries so that the average reads as the missing color, which removes the bands and replaces them with a fine grain over the whole picture. On a phone held close to the eye, that grain is visible. On a high resolution desktop panel it is less visible and the file has grown, because noise is the hardest thing to compress.
What to use instead, format by format
| Format | Colors | Use it for | Note |
|---|---|---|---|
| PNG | 16.7 million, lossless | Flat color, line art, text | Large files, no banding |
| JPEG | 16.7 million, lossy | Photographs | Bands badly on flat cel color |
| WebP | Lossy and lossless | Either | Roughly 25 to 35% smaller than JPEG |
| AVIF | Supports 10-bit | Either | Smaller again, and 10-bit largely removes banding |
| GIF | 256 | Short loops only | The palette is the problem |
For a still anime wallpaper, PNG is the safe choice and AVIF is the efficient one, and the reason is the same in both cases: neither is forced to throw colors away. For a moving one, the answer is not a better GIF, it is a video file, because every system that plays a moving wallpaper plays video and none of them needs an animated GIF to do it. A live wallpaper is a video your device never stops playing, and encoding that video as a GIF costs you the palette and gains you nothing.
Setting a moving wallpaper on a phone
To set a moving wallpaper on a phone, work with the slot the operating system actually provides rather than trying to make a GIF behave like one. On Android, the mechanism is a live wallpaper service, which apps register with the system; a GIF handed to the ordinary wallpaper picker is set as a single still frame, because the picker sets images and a GIF is an image as far as it is concerned. On iPhone, the animated lock screen slot takes a Live Photo, not a GIF, so a GIF saved to Photos has to be converted before iOS will treat it as anything but a still.
Both platforms have a shape problem underneath the format problem. Android panels are 1080 x 2400 in the mainstream and 1440 x 3120 on flagships, at aspect ratios of 20:9 and 19.5:9, which is taller than any aspect ratio artwork is ever composed in. A 16:9 image scaled to fill the height of a 19.5:9 phone needs to be about 3.85 times as wide as the screen, and everything outside that is cropped. Android also asks for a file wider than the screen so the launcher can scroll it, conventionally around twice the screen width where the launcher still supports parallax, and many no longer do. The same picture is a different file on every phone, and a GIF pulled from a board at whatever size somebody else uploaded it is almost never the right one. Free to download and free to use are not the same thing either, and a re-uploaded loop with no artist named is where that gap is widest.
Setting one on Windows and on a Mac
On Windows, the desktop background does not animate at all without extra software, so a GIF set through the ordinary personalization screen shows its first frame and stops. Wallpaper Engine is a Steam program that plays video, scenes and web pages behind the icons, and Lively Wallpaper and ScreenPlay are open source alternatives that cost nothing; all three take video files, and all three will take a GIF and convert or wrap it, which is a step that only exists because the GIF was the wrong container to start with.
Windows does one more thing worth knowing about even for still images: it re-encodes the desktop wallpaper as JPEG by default, which is why a clean PNG can look blocky the moment it is set. The behavior is controlled by a JPEGImportQuality value under HKEY_CURRENT_USER\Control Panel\Desktop, set as a DWORD between 60 and 100. On a flat cel shaded background this is the difference between clean color and visible blocking around the outlines.
On macOS there is no moving wallpaper slot you can fill with your own file. The system ships its own moving desktop pictures and its own dynamic desktops, and neither imports a GIF or a video you supply, so the cross platform open source option is the only route to a file of your own on that side.
When a GIF is still the right answer
A GIF is the right answer when the image genuinely has few colors and hard edges: pixel art, a two tone logo, a line drawing with no shading, a small looping element on a flat background. Those are the cases the format was built for, and in them a GIF is small, universal and lossless in practice. It is also right when the thing you are making is not a wallpaper at all, since a GIF is still the most portable way to post a short loop on the web.
For a high resolution anime wallpaper on a screen you look at all day, none of that applies. The picture wants every color it has, the panel can show them, and the only reason to reach for a 256 color format is that it was the file you happened to find.