手动将 CIE LChab 值转换为 RGB答案

【问题标题】：Convert manually CIE LChab values to RGB手动将 CIE LChab 值转换为 RGB
【发布时间】：2022-11-05 03:59:22
【问题描述】：

我想根据 CIE LHab 值显示 sRGB 值，我并不真正了解颜色理论的主题，但这是我的代码，我使用 colour library。我错过了什么？

#Use Illuminant d65 
d65 = [0.31382,0.33100]
# Maximun lightness of 100
lightess = 100
# Maximun chroma of 90
chroma = 90
# Create primary hue
hue = np.arange(0,360,45)

# Create np array
primary_rgb = np.array([[lightess,chroma, x] for x in hue])
# Convert to CIE L*a*b
primary_lab = colour.LCHab_to_Lab(primary_rgb) 
# Convert to XYZ 
primary_xyz =  colour.Lab_to_XYZ(primary_lab)
# Convert to sRGB color
primary_rgb = colour.XYZ_to_sRGB(primary_xyz,d65,'Bradford')
# Denormalize values 
primary_rgb*255

负值输出超出范围...

 array([[  409.91335532,   170.93938038,   260.71868158],
       [  393.03002494,   198.83037084,   134.96104706],
       [  300.27298956,   250.59731666,    58.49528246],
       [  157.31758891,   283.79165255,   123.85945153],
       [-1256.38350547,   296.51665099,   254.2577884 ],
       [-2417.70063864,   292.21019209,   380.58920247],
       [ -374.81508589,   264.85047515,   434.59056034],
       [  315.68646752,   211.99574857,   383.26874897]])

我想要一个正确的输出

【问题讨论】：

标签： colors hue color-space cielab xyz

【解决方案1】：

这里的问题是您正在构建一个覆盖大部分CIE 实验室空间，这样做，一些颜色，即负的颜色，将在外面sRGB色域：

import colour
import numpy as np

D65 = colour.CCS_ILLUMINANTS["CIE 1964 10 Degree Standard Observer"]["D65"]
hue = np.arange(0, 360, 45)
LCHab = colour.utilities.tstack([np.full(hue.shape, 100), np.full(hue.shape, 90), hue])
Lab = colour.LCHab_to_Lab(LCHab)
XYZ = colour.Lab_to_XYZ(Lab, D65)
sRGB = (
    colour.cctf_encoding(
        np.clip(colour.XYZ_to_sRGB(XYZ, apply_cctf_encoding=False), 0, 1)
    )
    * 255
)

print(sRGB)

figure, axes = colour.plotting.plot_RGB_colourspaces_in_chromaticity_diagram_CIE1976UCS(
    "sRGB", diagram_opacity=0.25, standalone=False
)
uv = colour.Luv_to_uv(colour.XYZ_to_Luv(XYZ, D65))
axes.scatter(uv[..., 0], uv[..., 1])
colour.plotting.render()

【讨论】：