GIF images
GIF uses indexed-colour image data and control records that can provide binary transparency and timed changes to a shared presentation canvas.
GIF stores image positions as indices into a colour table. A table can contain up to 256 entries. A file can use local colour tables for different images, so that limit should not be described as a universal maximum for all colours ever shown by an entire animation.
The index names a palette entry
An invented palette might be:
| Index | Defined colour | Use |
|---|---|---|
| 0 | Background colour | Filled positions |
| 1 | Dark lettering | Caption shape |
| 2 | Bright marker | Moving indicator |
Decoding index 1 recovers the entry's colour; the index itself is not an RGB component value.
Reducing a photographic source to an indexed palette can introduce colour grouping or dithering before the GIF's reversible coding. An exact decoding of those indices cannot recover the earlier photographic samples.
Transparency skips destination positions
A transparent-index declaration identifies positions that leave the existing destination unchanged. It supplies binary treatment rather than a full set of fractional alpha values around an edge.
A soft translucent logo converted into that model may need a different edge representation or a chosen background. The result can retain recognizable lettering while changing how it integrates with an Emby page.
An animation develops a canvas over time
A later image can cover only a rectangle within the logical canvas. The control information includes a delay and disposal behavior, determining whether earlier drawn content remains or is replaced/restored after presentation.
For an invented sequence with delays 2, 3 and 5 hundredths of a second, the nominal loop duration is 0.10 seconds. A consumer's scheduling and delay policy can affect the observed playback.
The animated-image article shows why a small frame rectangle is not necessarily a complete standalone picture. A gallery thumbnail needs a reconstructed canvas at a selected instant, rather than blindly saving the latest rectangle.