File Under: Glossary

Interlaced

If a computer-displayed image is interlaced, then it is rendered in alternating horizontal lines.

For example, browsers display interlaced GIFs in alternating passes, skipping every other line and rendering a kind of blurry image first and then sharpening it on subsequent passes. This is useful if you’d like your viewers to get a general idea of the image while they are downloading it. Interlacing for GIFs was designed to make bigger images quicker to download, but the problem is that an interlaced GIF actually has a larger file size than a non-interlaced GIF, so use this method cautiously.