[BUG]: README 'Blackbody' graph is empty

[mm2t]

Description

Why is the blackbody spectral power graph empty?

Also, may I suggest a more intuitive label for the y axis. "Radiance"?

Code for Reproduction

Exception Message

Environment Information

[Ig0rFB]

@mm2t It's not actually empty. I just tested it and what appears to be happening is that the line colours are derived from the computed spectra, and they are very very light and almost impossible to see against the white bg.
You can test this by either flipping the bg to black or changing the line colours:

import colour
import numpy as np
from colour.plotting import *

blackbody_sds = [
colour.sd_blackbody(i, colour.SpectralShape(1, 10001, 10))
for i in range(1000, 15000, 1000)
]
start_colour = np.array([0.55, 0.08, 0.02])
end_colour = np.array([0.92, 0.92, 0.9])
gradient_colours = np.linspace(start_colour, end_colour, len(blackbody_sds))

plot_multi_sds(
blackbody_sds,
y_label="W / (sr m$^2$) / m",
plot_kwargs=[
{"color": tuple(colour_RGB), "linewidth": 2.0}
for colour_RGB in gradient_colours
],
legend_location="upper right",
bounding_box=(0, 1250, 0, 2.5e6),
)

[KelSolaar]

Hi, Yes this is because the plot is set to use the spd colours, none side effect :) For that specific figure, we should switch the bg to average gray or alike. Thomas Mansencal - colour-science.org <https://www.colour-science.org> - thomasmansencal.com <http://www.thomasmansencal.com>

…

On Fri, 27 Mar 2026 at 9:31 AM, Igor B ***@***.***> wrote: *Ig0rFB* left a comment (colour-science/colour#1387) <#1387 (comment)> @mm2t <https://github.com/mm2t> It's not actually empty. I just tested it and what appears to be happening is that the line colours are derived from the computed spectra, and they are very very light and almost impossible to see against the white bg. You can test this by either flipping the bg to black or changing the line colours: import colour import numpy as np from colour.plotting import * blackbody_sds = [ colour.sd_blackbody(i, colour.SpectralShape(1, 10001, 10)) for i in range(1000, 15000, 1000) ] start_colour = np.array([0.55, 0.08, 0.02]) end_colour = np.array([0.92, 0.92, 0.9]) gradient_colours = np.linspace(start_colour, end_colour, len(blackbody_sds)) plot_multi_sds( blackbody_sds, y_label="W / (sr m$^2$) / m", plot_kwargs=[ {"color": tuple(colour_RGB), "linewidth": 2.0} for colour_RGB in gradient_colours ], legend_location="upper right", bounding_box=(0, 1250, 0, 2.5e6), ) — Reply to this email directly, view it on GitHub <#1387?email_source=notifications&email_token=AAAYLQZ7VS34XXXK2W6C4ZD4SWHRLA5CNFSNUABFM5UWIORPF5TWS5BNNB2WEL2JONZXKZKDN5WW2ZLOOQXTIMJTHAYDCNZVGY3KM4TFMFZW63VKON2WE43DOJUWEZLEUVSXMZLOOSWGM33PORSXEX3DNRUWG2Y#issuecomment-4138017566>, or unsubscribe <https://github.com/notifications/unsubscribe-auth/AAAYLQYJGC7NO7C4ZU6MQZD4SWHRLAVCNFSM6AAAAACQ5WP3KCVHI2DSMVQWIX3LMV43OSLTON2WKQ3PNVWWK3TUHM2DCMZYGAYTONJWGY> . You are receiving this because you are subscribed to this thread.Message ID: ***@***.***>