What is SIXEL format?

SIXEL (DEC SIXEL Graphics Format)

Sixel is a graphics format originally developed for the DEC VT340 terminal in the 1980s, designed to enable the transmission of bitmap images over text-based communication channels. The name 'sixel' derives from the six-pixel-wide encoding scheme it employs, which allows image data to be embedded directly into terminal output. This capability made it possible to display images in terminal emulators that typically only support plain text, thus enhancing the visual experience of users in command-line interfaces.

The format encodes pixel information in a compact manner, leveraging a combination of control characters and data bytes to represent color and pixel positioning. Sixel graphics can support a palette of up to 64 colors, which is sufficient for many simple images and graphics, making it ideal for applications in specific environments like scientific visualization or retro computing.

One of the notable advantages of the Sixel format is its efficiency in terms of data size compared to other bitmap image formats. This efficiency is particularly valuable in low-bandwidth scenarios where minimizing data transfer is essential. Additionally, since Sixel images can be rendered directly in the terminal, they allow for interactive and dynamic visual content without the need for external image viewing applications.

Various modern terminal emulators have adopted support for Sixel graphics, enabling users to easily view images directly in their command-line interfaces. This has reinvigorated interest in the format among developers and users who appreciate the blending of graphical and textual information in terminal applications. Sixel is often used in conjunction with tools that output graphics as part of their functionality, such as plotting libraries and command-line image viewers.

Despite being less commonly known than other image formats, Sixel serves a niche but important purpose in environments where graphical capabilities are limited or where users prefer terminal-based interfaces. Its simplicity and effectiveness make it a useful tool for developers looking to enhance terminal applications with graphical outputs.

What programs can open SIXEL format?

  • xterm
  • mlterm
  • iTerm2
  • Kitty
  • Terminology
  • Sixel Terminal

Use cases for SIXEL format?

  • Displaying images in terminal emulators
  • Integrating graphics in command-line applications
  • Visualizing data and plots in text-based environments
  • Creating retro computing experiences
  • Rendering diagnostic images in remote server management