5 ms·

Sixel: A terminal bitmap graphics format from the 80s

54 points by unwind 4y ago

karmakaze 4y ago
The TRS-80 had 2x3 matrix block characters[0] in the character code range 128-191 that apparently were called squots (square dots). Combined with direct memory read/write, a decent CPU and fast basic made for some easy game dev of the snake and ski variety. [0] https://www.trs-80.com/wordpress/tips/graphics/ https://www.trs-80.com/wordpress/tips/graphics/
- musicale 4y ago
  On the Model 3 it seems to be possible to race the beam to double the vertical resolution. http://48k.ca/128x192.html http://48k.ca/128x192.html
  - karmakaze 4y ago
    That's cool to be able to do using character generated graphics.
globalreset 4y ago
It's an ancient and crappy standard. No point in trying to resurrect it now. https://sw.kovidgoyal.net/kitty/graphics-protocol/ https://sw.kovidgoyal.net/kitty/graphics-protocol/
- csdvrx 4y ago
  I see you are as objective, impartial and opiniated as the author of the terminal you are referencing /s
  - all2 4y ago
    GP's opinion is objectively correct. I fail to see the relevance of your assertion. /s
- anticrymactic 4y ago
  Great to see that Lenna is still in use
frankjr 4y ago
curl https://raw.githubusercontent.com/saitoha/libsixel/master/images/snake.six
shrubble 4y ago
Note that notcurses.com has a video demo of their library using Sixel, though the background music may be nsfw...
hedora 4y ago
How did they do the shading of the wikipedia logo in the article? It doesn’t appear to be dithered.
- flohofwoe 4y ago
  Sixels is a paletted bitmap format, and (AFAIK) some terminals support more than 256 colors (e.g. see the screenshot in the readme here: https://github.com/saitoha/libsixel https://github.com/saitoha/libsixel). But I guess the Wikipedia logo looks just fine with 256 colors.
mnurzia 4y ago
Whenever Sixel comes up, I always think about this guy who wrote terminal patches that allowed for Sixel support, as well as a library (libsixel) that generates them: https://github.com/saitoha https://github.com/saitoha A couple years ago, it seemed like he was on a mission to patch every terminal in existence so that Sixel support was widespread. Seriously, half of his repositories have something to do with Sixel. Back then I was still on Windows, and when he patched mintty it was kind of crazy seeing bitmap graphics in my terminal for the first time. It seems as though he hasn't made any commits in years, though. I wonder what happened to him. I always admired his interest in pushing these graphics, however old and arcane the protocol may be.
justusw 4y ago
The fact that xterm supports Sixel, at least through a build flag, once more confirms my belief that this old and battle tested terminal emulator very much rocks.
3np 4y ago
It turns out there is an active sixel branch of tmux. Scrolling is a bit broken (as in parts of images blank out when scrolling) but otherwise it works fine in mlterm (variable-width fonts ftw). So far they have merged past progress to a sixel branch on the upstream repo so it seems to be a matter of progress until it's merged. https://github.com/topcat001/tmux/tree/sixel https://github.com/topcat001/tmux/tree/sixel
flohofwoe 4y ago
I experimented a bit with Sixel output for a home computer emulator, but good Sixel support in terminals is hard to come by (e.g. iTerm2 on Mac theoretically supports Sixels, but it's way too slow for any sort of realtime output beyond 4 colors). I wish there was a proper (and widely supported) framebuffer standard for terminals with a 'chunky pixel format'.
- musicale 4y ago
  I wish the regular Terminal app had fast sixel support.
lproven 4y ago
WordPerfect for UNIX™ now runs natively on Linux thanks to the amazing Tavis Ormandy's work, and he has got it generating print previews in the terminal using sixels: https://lock.cmpxchg8b.com/wordperfect.html https://lock.cmpxchg8b.com/wordperfect.html
musicale 4y ago
I wish Terminal supported this in macOS.
gaudat 4y ago
Is there a terminal emulator supporting this mode?
- badsectoracula 4y ago
  There are a bunch. For example xterm does[0]. You can find a list with terminals that support it at [1]. [0] https://i.imgur.com/yD6aVQa.png https://i.imgur.com/yD6aVQa.png [1] https://www.arewesixelyet.com https://www.arewesixelyet.com

54 points by unwind 4y ago

The TRS-80 had 2x3 matrix block characters[0] in the character code range 128-191 that apparently were called squots (square dots). Combined with direct memory read/write, a decent CPU and fast basic made for some easy game dev of the snake and ski variety. [0] https://www.trs-80.com/wordpress/tips/graphics/ https://www.trs-80.com/wordpress/tips/graphics/

musicale 4y ago
On the Model 3 it seems to be possible to race the beam to double the vertical resolution. http://48k.ca/128x192.html http://48k.ca/128x192.html
- karmakaze 4y ago
  That's cool to be able to do using character generated graphics.

globalreset 4y ago

It's an ancient and crappy standard. No point in trying to resurrect it now. https://sw.kovidgoyal.net/kitty/graphics-protocol/ https://sw.kovidgoyal.net/kitty/graphics-protocol/

csdvrx 4y ago
I see you are as objective, impartial and opiniated as the author of the terminal you are referencing /s
- all2 4y ago
  GP's opinion is objectively correct. I fail to see the relevance of your assertion. /s
anticrymactic 4y ago
Great to see that Lenna is still in use

frankjr 4y ago

curl https://raw.githubusercontent.com/saitoha/libsixel/master/images/snake.six

shrubble 4y ago

Note that notcurses.com has a video demo of their library using Sixel, though the background music may be nsfw...

hedora 4y ago

How did they do the shading of the wikipedia logo in the article? It doesn’t appear to be dithered.

flohofwoe 4y ago
Sixels is a paletted bitmap format, and (AFAIK) some terminals support more than 256 colors (e.g. see the screenshot in the readme here: https://github.com/saitoha/libsixel https://github.com/saitoha/libsixel). But I guess the Wikipedia logo looks just fine with 256 colors.

mnurzia 4y ago

Whenever Sixel comes up, I always think about this guy who wrote terminal patches that allowed for Sixel support, as well as a library (libsixel) that generates them: https://github.com/saitoha https://github.com/saitoha A couple years ago, it seemed like he was on a mission to patch every terminal in existence so that Sixel support was widespread. Seriously, half of his repositories have something to do with Sixel. Back then I was still on Windows, and when he patched mintty it was kind of crazy seeing bitmap graphics in my terminal for the first time. It seems as though he hasn't made any commits in years, though. I wonder what happened to him. I always admired his interest in pushing these graphics, however old and arcane the protocol may be.

justusw 4y ago

The fact that xterm supports Sixel, at least through a build flag, once more confirms my belief that this old and battle tested terminal emulator very much rocks.

3np 4y ago

It turns out there is an active sixel branch of tmux. Scrolling is a bit broken (as in parts of images blank out when scrolling) but otherwise it works fine in mlterm (variable-width fonts ftw). So far they have merged past progress to a sixel branch on the upstream repo so it seems to be a matter of progress until it's merged. https://github.com/topcat001/tmux/tree/sixel https://github.com/topcat001/tmux/tree/sixel

flohofwoe 4y ago

I experimented a bit with Sixel output for a home computer emulator, but good Sixel support in terminals is hard to come by (e.g. iTerm2 on Mac theoretically supports Sixels, but it's way too slow for any sort of realtime output beyond 4 colors). I wish there was a proper (and widely supported) framebuffer standard for terminals with a 'chunky pixel format'.

musicale 4y ago
I wish the regular Terminal app had fast sixel support.

lproven 4y ago

WordPerfect for UNIX™ now runs natively on Linux thanks to the amazing Tavis Ormandy's work, and he has got it generating print previews in the terminal using sixels: https://lock.cmpxchg8b.com/wordperfect.html https://lock.cmpxchg8b.com/wordperfect.html

musicale 4y ago

I wish Terminal supported this in macOS.

gaudat 4y ago

Is there a terminal emulator supporting this mode?

badsectoracula 4y ago
There are a bunch. For example xterm does[0]. You can find a list with terminals that support it at [1]. [0] https://i.imgur.com/yD6aVQa.png https://i.imgur.com/yD6aVQa.png [1] https://www.arewesixelyet.com https://www.arewesixelyet.com