RGB to xterm/oklch

OUTPUT.png

requirements-dev.in

ipython
matplotlib
black
isort

requirements-dev.txt

#
# This file is autogenerated by pip-compile with python 3.10
# To update, run:
#
#    pip-compile --no-emit-trusted-host requirements-dev.in
#
asttokens==2.1.0
    # via stack-data
backcall==0.2.0
    # via ipython
black==22.10.0
    # via -r requirements-dev.in
click==8.1.3
    # via black
colorama==0.4.6
    # via
    #   click
    #   ipython
contourpy==1.0.6
    # via matplotlib
cycler==0.11.0
    # via matplotlib
decorator==5.1.1
    # via ipython
executing==1.2.0
    # via stack-data
fonttools==4.38.0
    # via matplotlib
ipython==8.6.0
    # via -r requirements-dev.in
isort==5.10.1
    # via -r requirements-dev.in
jedi==0.18.1
    # via ipython
kiwisolver==1.4.4
    # via matplotlib
matplotlib==3.6.2
    # via -r requirements-dev.in
matplotlib-inline==0.1.6
    # via ipython
mypy-extensions==0.4.3
    # via black
numpy==1.23.5
    # via
    #   contourpy
    #   matplotlib
packaging==21.3
    # via matplotlib
parso==0.8.3
    # via jedi
pathspec==0.10.2
    # via black
pickleshare==0.7.5
    # via ipython
pillow==9.3.0
    # via matplotlib
platformdirs==2.5.4
    # via black
prompt-toolkit==3.0.32
    # via ipython
pure-eval==0.2.2
    # via stack-data
pygments==2.13.0
    # via ipython
pyparsing==3.0.9
    # via
    #   matplotlib
    #   packaging
python-dateutil==2.8.2
    # via matplotlib
six==1.16.0
    # via python-dateutil
stack-data==0.6.1
    # via ipython
tomli==2.0.1
    # via black
traitlets==5.5.0
    # via
    #   ipython
    #   matplotlib-inline
wcwidth==0.2.5
    # via prompt-toolkit

requirements.in

colour-science
numpy

requirements.txt

#
# This file is autogenerated by pip-compile with python 3.10
# To update, run:
#
#    pip-compile --no-emit-trusted-host requirements.in
#
colour-science==0.4.1
    # via -r requirements.in
imageio==2.22.4
    # via colour-science
numpy==1.23.5
    # via
    #   -r requirements.in
    #   colour-science
    #   imageio
    #   scipy
pillow==9.3.0
    # via imageio
scipy==1.9.3
    # via colour-science
typing-extensions==4.4.0
    # via colour-science

rgb_to_xterm.py

from math import atan2, degrees, pow, sqrt

import colour
import numpy as np


def xtermLUT(readable_blue=True):
    #   0 -   7 : primary
    #   9 -  15 : primary (bright)
    return np.uint8(
        [
            [0, 0, 0],
            [205, 0, 0],
            [0, 205, 0],
            [205, 205, 0],
            [0, 0, 238],
            [205, 0, 205],
            [0, 205, 205],
            [229, 229, 229],
        ]
        + [
            [127, 127, 127],
            [255, 0, 0],
            [0, 255, 0],
            [255, 255, 0],
            [92, 92, 255] if readable_blue else [0, 0, 255],
            [255, 0, 255],
            [0, 255, 255],
            [255, 255, 255],
        ]
    )


def vgaLUT():
    #   0 -   7 : primary
    #   9 -  15 : primary (bright)
    return np.uint8(
        [
            [0, 0, 0],
            [170, 0, 0],
            [0, 170, 0],
            [170, 85, 0],
            [0, 0, 170],
            [170, 0, 170],
            [0, 170, 170],
            [170, 170, 170],
        ]
        + [
            [85, 85, 85],
            [255, 85, 85],
            [85, 255, 85],
            [255, 255, 85],
            [85, 85, 255],
            [255, 85, 255],
            [85, 255, 255],
            [255, 255, 255],
        ]
    )


def xtermLUT(base=xtermLUT):
    #  16 - 231 : 6x6x6 cube
    # 232 - 255 : gray scale (23 colors)
    lut = []
    m = [0, 0x5F, 0x87, 0xAF, 0xD7, 0xFF]
    for r in range(0, 6):
        r = m[r]
        for g in range(0, 6):
            g = m[g]
            for b in range(0, 6):
                lut.append([r, g, m[b]])
    assert len(lut) == 216
    # gray
    for i in range(0, 24):
        lut.append([8 + i * 10] * 3)
    assert len(lut) == 240
    return np.concatenate((base(), np.uint8(lut)), axis=0)


def unhexrgb(s: str) -> list:
    if s[0] == "#":
        s = s[1:]
    if len(s) == 3:
        rgb = list(int(c, 16) for c in s)
    elif len(s) == 6:
        rgb = list(int(s[i : i + 2], 16) for i in range(0, 6, 2))
    else:
        raise Exception(f"unknown color format {s}")
    return np.uint8(rgb)


def hexrgb(rgb) -> str:
    assert len(rgb) == 3
    assert all(0.0 <= x < 256.0 for x in rgb)
    return f"#{int(rgb[0]):02X}{int(rgb[1]):02X}{int(rgb[2]):02X}"


def scale(rgb):
    """RGB 0 - 255 reduced to 0.0-1.0 scale."""
    return colour.io.convert_bit_depth(rgb, "float32")


def unscale(rgb):
    """RGB 0.0 - 1.0 reduced to 0-255 scale."""
    return colour.io.convert_bit_depth(rgb, "uint8")


def RGB_to_Oklab(rgb: list) -> list:
    assert len(rgb) == 3
    assert all(0 <= x < 256 for x in rgb)
    xyz = colour.sRGB_to_XYZ(scale(rgb))
    return colour.XYZ_to_Oklab(xyz)


def RGB_to_Oklch(rgb: list) -> list:
    l, a, b = RGB_to_Oklab(rgb)
    k1, k2, k3 = 0.206, 0.03, 1.206 / 1.03
    lr = (k3 * l - k1 + sqrt(pow(k3 * l - k1, 2) + 4 * k2 * k3 * l)) / 2
    c = sqrt(a * a + b * b)
    h = degrees(atan2(b, a))
    if h < 0:
        h += 360
    return [l, c, h]


def RGB_to_Lab(rgb: list) -> list:
    assert len(rgb) == 3
    assert all(0 <= x < 256 for x in rgb)
    return colour.XYZ_to_Lab(colour.sRGB_to_XYZ(scale(rgb)))


def Lab_to_RGB(rgb: list) -> list:
    assert len(rgb) == 3
    return unscale(colour.XYZ_to_sRGB(colour.Lab_to_XYZ(rgb)))


XTERM_LAB = np.array([RGB_to_Lab(color) for color in xtermLUT()])


def xterm_lut(rgb):
    terms = XTERM_LAB[16:]
    lab = RGB_to_Lab(rgb)
    k, m = -1, 256
    for i, e in enumerate(colour.delta_E(lab, x) for x in terms):
        if e < m:
            k, m = i, e
    return k + 16, xtermLUT()[k + 16]


def truecolor(rgb):
    return f"\033[48;2;{rgb[0]};{rgb[1]};{rgb[2]}m"


def bg0():
    return f"\033[0m"


def display(colors):
    terms = xtermLUT()
    for name, color in colors.items():
        n, xterm_rgb = xterm_lut(color)
        print(f"{name:<20s} {hexrgb(color)} {hexrgb(xterm_rgb)}/{n:3}", end=" ")
        print(
            f"{truecolor(color)}   {bg0()} {truecolor(xterm_rgb)}   {bg0()}", end=" | "
        )
        l, c, h = RGB_to_Oklch(color)
        print(f"{l*100:5.1f}%  {c:4.2f}  {int(h):3}", end=" | ")
        l, c, h = RGB_to_Oklch(xterm_rgb)
        print(f"{l*100:5.1f}%  {c:4.2f}  {int(h):3}")


def main():
    print("----- yellow")
    display(
        {
            "central color": unhexrgb("#FF8700"),
            "selected window bg": unhexrgb("#5F5FFF"),
            "hidden window text": unhexrgb("#000087"),
            "level 1 text": unhexrgb("#000087"),
            "level 1 background": unhexrgb("#FFAF00"),
            "level 2 text": unhexrgb("#000087"),
            "level 2 background": unhexrgb("#FFD700"),
            "level 3 text": unhexrgb("#5F5FFF"),
            "level 3 background": unhexrgb("#FFFF00"),
        }
    )
    print("----- blue")
    display(
        {
            "central color": unhexrgb("#5F5FFF"),
            "selected window bg": unhexrgb("#FFD700"),
            "hidden window text": unhexrgb("#FFAF00"),
            "level 1 text": unhexrgb("#FFD700"),
            "level 1 background": unhexrgb("#5F87FF"),
            "level 2 text": unhexrgb("#FFFFAF"),
            "level 2 background": unhexrgb("#5FD7FF"),
            "level 3 text": unhexrgb("#5F5FFF"),
            "level 3 background": unhexrgb("#5FFFFF"),
        }
    )
    print("----- blue2")
    display(
        {
            "central color": unhexrgb("#2D4BC5"),
            "selected window bg": unhexrgb("#FFE700"),
            "hidden window text": unhexrgb("#FFC952"),
            "level 1 text": unhexrgb("#FFDA24"),
            "level 1 background": unhexrgb("#5B70FF"),
            "level 2 text": unhexrgb("#FFEE99"),
            "level 2 background": unhexrgb("#00B2FF"),
            "level 3 text": unhexrgb("#5F5FFF"),
            "level 3 background": unhexrgb("#24F2FF"),
        }
    )


if __name__ == "__main__":
    main()