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:
PlanckianLocus. CIE xy chromaticity diagram including the Planckian Locus The Planckian locus is the path that black body color will take through the diagram as the black body temperature changes Lines crossing the locus indicate lines of constant correlated color temperature Monochromatic wavelengths are shown in blue in units