Can we plot triangle in CIE 1931 with custom points

[nitishn23]

Hello ,

I would like to plot a triangle in CIE 1931 colour space as below image.

Cutsom triangle coordinates:
CIE 1931 x CIE 1931 y
0.690 0.310
0.170 0.720
0.150 0.030

[KelSolaar]

Hi @nitishn23,

Yes this is easy:

import colour

RGB_COLOURSPACE_CUSTOM = colour.RGB_Colourspace(
    "Custom",
    [[0.690, 0.310], [0.170, 0.720], [0.150, 0.030]],
    colour.CCS_ILLUMINANTS["CIE 1931 2 Degree Standard Observer"]["D65"],
)

colour.plotting.plot_RGB_colourspaces_in_chromaticity_diagram_CIE1931(
    RGB_COLOURSPACE_CUSTOM, plot_kwargs={"color": "y"}
)

[nitishn23]

Hi @KelSolaar Thanks this works well for me.

Any idea how to get these highlighted x,y coordinates of colour selected on the plot, my purpose is I want to pass these coordinates to different function. Allow user to select the colour from the region highlted and get the coordinates

[KelSolaar]

Matplotlib’s Event Handling should give you click coordinates: https://matplotlib.org/stable/users/explain/event_handling.html

[nitishn23]

Thanks @KelSolaar i could work it out with this, I was trying to convert XYZ to RGB values using this XYZ_to_RGB. RGB=XYZ_to_RGB(
XYZ,
illuminant_XYZ,
illuminant_RGB,
matrix_XYZ_to_RGB,
)

My output is like this RGB=[ 85.56690369 26.05828243 155.7562224 ], How can i get these individual values of these array when i try accessing RGB[0], RGB[1],RGB[2] it gives me a wrong value.

[KelSolaar]

Are you sure your output is 1D? Would you mind printing RGB.shape please?

[nitishn23]

Ohh now i get the values correct, earlier i was scaling them to 255 and printing the individual array values that creates a problem.
Thank for the quick response