This image was acquired from
wikimedia. It was marked as Public Domain or CC0 and is free to use. To verify, go to the source and check the information there.
Keywords from Image Description:
Blackbody sRGB quantalunits. CIE XYZ tristimulus version modified by Judd and Vos ioo ucl ac uk htm weighted by reciprocal wavelength for quantal scaling with int infty lambda overline lambda frac lambda lambda dlambdaY int infty lambda overline lambda frac lambda lambda dlambdaZ int infty lambda overline lambda frac