sixel graphics
also: DEC sixel, sixel protocol
A compact image format that encodes bitmap graphics as escape sequences, allowing terminal emulators to display images directly in the terminal without external viewers.
Sixel is a graphics protocol developed by DEC (Digital Equipment Corporation) that encodes images as text-based escape sequences. Each character in a sixel stream represents a 6×1 pixel cell, with color information encoded in the sequence. Modern terminal emulators like xterm, kitty, and iTerm2 support sixel rendering.
Sixel is efficient for terminal graphics because the encoded data is relatively compact and can be transmitted over serial connections or SSH sessions. Unlike bitmap images, sixel data is text-based, making it compatible with standard terminal protocols.
Example use case: img2sixel photo.jpg | less displays an image in your terminal. Tools like chafa and ImageMagick can convert standard image formats (PNG, JPEG) to sixel format for terminal display.