GIF format

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

The format was designed for transmitting bitmap images over the Internet. GIF has a color palette consisting of 256 colors. The GIF algorithm chooses the 256 colors that are the most used in the original image, and it creates all of the other shades by mixing and matching the neighboring pixels so that the human eye perceives them as the desired color. This is why the GIF format is not suitable for storing full-color images and photographs and why it is suitable for very 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.

Recently, GIF images have started to be used less frequently, since they have been replaced by other, more optimal formats.

Thus, the GIF format is suitable if:

• You need a very simple animation.

Actually, there is one other image format we need to mention, called WebP. It supports lossy and lossless compression, as well as animation and alpha transparency, and is a smaller file size than JPG or PNG. However, Safari doesn’t support it. It can, however, be used in conjunction with the <picture> tag to deliver an image that will work in Safari too, but that is an advanced topic that is out of scope for this chapter.