GIF format

The last image format that we’ll cover in this chapter is GIF.

GIF was designed for transmitting bitmap images. Each image uses a palette of up to 256 colors. When converting a full-color image to GIF, an encoder chooses a limited palette. It may use patterns of neighboring pixels to give the impression of additional shades; this is called dithering. The limited palette makes GIF less suitable for photographs with many colors and subtle gradients. GIF also supports multiple frames, making it useful for simple animations.

The format supports transparency: each pixel in the image can be in one of two states: transparent or opaque. Translucency is not supported.

GIF remains useful for simple animations, though other formats can offer better compression and color support.

Thus, the GIF format is suitable if:

• You need a very simple animation.

One more format is worth mentioning: WebP. It supports lossy and lossless compression, animation and alpha transparency. WebP often produces smaller files than JPEG or PNG, depending on the image and settings. Modern browsers, including Safari, support it. The <picture> tag can provide alternative image formats when needed, but that is an advanced topic outside the scope of this chapter.