Colors in terminal

It's a common confusion about terminal colors... Actually we have this:

plain ascii
ansi escape codes (16 color codes with bold/italic and background)
256 color palette (216 colors+16gray + ansi) (colors are 24bit)
24bit true color (888 colors (aka 16 milion))

The 256 color palete is configured at start, and it's a 666 cube of colors, each of them defined as a 24bit (888 rgb) color.

This means that current support can only display 256 different colors in the terminal, while truecolor means that you can display 16 milion different colors at the same time.

Truecolor escape codes doesnt uses a color palete. It just specifies the color itself.

Here's a test case:

printf "\x1b[38;2;255;100;0mTRUECOLOR\x1b[0m\n"

Keep in mind that it is possible to use both ';' and ':' as parameters delimiter.

According to Wikipedia[1], this is only supported by xterm and konsole.

[1] https://en.wikipedia.org/wiki/ANSI_color

Here are terminals discussions:

Now supporting truecolor

st (from suckless) [delimeter: semicolon] - http://lists.suckless.org/dev/1307/16688.html
konsole [delimeter: colon, semicolon] - https://bugs.kde.org/show_bug.cgi?id=107487
iterm2 [delimeter: colon, semicolon] - only in the nighties https://code.google.com/p/iterm2/issues/detail?id=218
qterminal [delimeter: semicolon] - lxqt/qterminal#78
Tera Term [delimeter: colon, semicolon] - Windows platform
FinalTerm [delimeter: semicolon]
all libvte based terminals (since 0.36 version) [delimeter: colon, semilocon] - https://bugzilla.gnome.org/show_bug.cgi?id=704449
- libvte-based Gnome Terminal
- libvte-based sakura
- libvte-based Terminator
- libvte-based Lilyterm - since commit https://github.com/Tetralet/LilyTerm/commit/72536e7ba448ad9ef1126ce45fbde3a3407a271b
- libvte-based ROXTerm
- libvte-based evilvte - no release yet, version from git https://github.com/caleb-/evilvte
- libvte-based Termit
- libvte-based Termite
- libvte-based Tilda
- libvte-based tinyterm

But there are bunch of libvte-based terminals for GTK2 so they are listed in the another section.

Parsing ANSI color sequences, but approximating them to 256 palette

xterm (though doing it wrong: "it uses nearest colour in RGB colour space, with a usualfalse assumption about orthogonal axes")
mlterm - http://sourceforge.net/mailarchive/message.php?msg_id=31828705

Note about colour differences: a) RGB axes are not orthogonal, so you cannot use sqrt(R^2+G^2+B^2) formula, b) for colour differences there is more correct (but much more complex) CIEDE2000 formula (which may easily blow up performance if used blindly) [2].

[2] neovim/neovim#793 (comment)