[PATCH] improve truecolor accuracy

[Emanuele Giaquinta]

Hi,

On Sun, Feb 16, 2020 at 08:01:08PM +0800, Fengguang Wu wrote:
> Introduce color_level[][] to
> 
> - select more close neighbors
> 
> - avoid pure red and green and blue colors to
>  interact with each other obviously in the first level
> 
> The attached images show the changes vividly. Created this way:
> 
> Step 1) run 24-bit-color.sh
> Step 2) switch to other window and then back
> Step 3) run 24-bit-color.sh
> Step 4) run 256-color-codes.rb
> 
> Before patch, there are 2 major issues:
> 
> Issue 1) the first half of the first RED/BLUE row of (1) becomes BLUE
>         colors. Which can be a big supprise to end users.
> 
> Issue 2) the right bottom of (4) has blue background for color code
>         38;5;256, which should be white instead.
> 
> After patch, the above issues are fixed. Output looks smoother too.
> 
> There is still one minor issue: output from (1) and (3) will differ in
> minor ways. Such kind of unstableness exists even when disabled the
> neighbor logic.
> 
> color_level[][] is created by this script, with the unconfirmed
> assumption that delta in smaller rgb values might be more sensible to
> human eye. At least the smaller range for level 0 fixed issue (1).

applied, thanks.

Emanuele