ThumbHash
A very compact representation of an image placeholder
ThumbHash is a compact image placeholder format designed to give visually rich, low-bandwidth previews while the full image loads. It encodes an image into a tiny byte array that captures approximate colors, gradients, and aspect ratio, then decodes that array back into a blurred thumbnail at render time. Unlike simple color blocks or very low-resolution thumbnails, ThumbHash packs more detail per byte and includes alpha support, so it works well even for images with transparency. The design intentionally targets inlined storage: hashes are small enough to live directly in JSON payloads, databases, or HTML attributes without ballooning page size. ...