Which colors of light the human eye sees best

Name: Which colors of light the human eye sees best
Creator: Unlabeled
License: CC BY-SA 4.0

In daylight the eye is most sensitive at 555 nm, a yellow-green. Red light at 655 nm must be 12 times as strong to look as bright. In dim light the peak moves to 507 nm.

What does this axis measure?

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y ↑: Eye's sensitivity (peak = 1)
x →: Wavelength of light (nm)

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The data: 37 points

Wavelength of light (nm)	Eye's sensitivity (peak = 1)
395	0.0002
405	0.0006
415	0.0022
425	0.0073
435	0.0168
445	0.0298
455	0.048
465	0.0739
475	0.1126
485	0.1693
495	0.2586
505	0.4073
515	0.6082
525	0.7932
535	0.9149
545	0.9803
555	1
565	0.9786
575	0.9154
585	0.8163
595	0.6949
605	0.5668
615	0.4412
625	0.321
635	0.217
645	0.1382
655	0.0816
665	0.0446
675	0.0232
685	0.0119
695	0.0057
705	0.0029
715	0.0015
725	0.0007
735	0.0004
745	0.0002
755	0.0001

Source: International Commission on Illumination (CIE), spectral luminous efficiency for photopic and scotopic vision, V(λ) and V′(λ), CIE 018:2019 (DOIs 10.25039/CIE.DS.dktna2s3 and 10.25039/CIE.DS.gr6w4b5g); colors after the solve from the CIE 1931 color-matching functions (DOI 10.25039/CIE.DS.xvudnb9b), converted to sRGB by Unlabeled
Licence: CC BY-SA 4.0
Read: 2026-11-05
Drawn: 37 points as the puzzle showed them · line

Ran in puzzle #42 on November 7, 2026. Play it

Which colors of light the human eye sees best

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