HVIF format used by Haiku for icons aims to keep vector icon files as small as possible, allowing for the display of icons in various sizes while still fitting into file metadata. Unlike other OSes that use bitmaps, Haiku’s HVIF format is optimized for abstract, symbolic icons, not file previews. This format helps reduce disk reads when displaying icons in a folder by storing icons within file metadata. By dissecting an example icon using a hex editor, the blog post highlights an optimization bug in the icon image editor. The efficiency of the HVIF format lies in its compact file size and ability to render icons at various sizes without distortion, making it a unique and efficient solution for icon representation.
http://blog.leahhanson.us/post/recursecenter2016/haiku_icons.html