Colours in terminal
It's a common confusion about terminal colours... Actually we have this:
- plain ascii
- ansi escape codes (16 colour codes with bold/italic and background)
- 256 colour palette (216 colours + 16 ansi + 24 gray) (colors are 24bit)
- 24bit true colour ("888" colours (aka 16 milion))
The 256 colour palete is configured at start, and it's a 666 cube of
colours, each of them defined as a 24bit (888 rgb) colour.
This means that current support can only display 256 different colours
in the terminal, while truecolour means that you can display 16 milion
different colours at the same time.
Truecolour escape codes doesnt uses a colour palete. It just specifies the
Here's a test case:
Keep in mind that it is possible to use both ';' and ':' as parameters delimiter.
According to Wikipedia, this is only supported by xterm and konsole.
Currently, there is no support for the 24-bit colour descriptions in the terminfo/termcap database and utilites.
See the discussion thread here: https://lists.gnu.org/archive/html/bug-ncurses/2013-10/msg00007.html
Here are terminals discussions:
Now supporting truecolour
But there are bunch of libvte-based terminals for GTK2 so they are listed in the another section.
Also, while this one is not exactly a terminal, but a terminal replayer, it still worth mentioning:
Parsing ANSI colour sequences, but approximating them to 256 palette
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) .
NOT supporting truecolour
 You can download patched version here https://github.com/rdebath/PuTTY
 You can download patched version here https://github.com/halcy/PuTTY
Here are another console programs discussions:
Supporting True Colour:
Not supporting True Colour: