Dietrich Zawischa

Is there a shortcut to obtain RGB values?

First a quotation from Dan Bruton's site with the heading "Color Science":

SPECTRA
The spectra to the right were generated using different RGB values for wavelengths between 380nm and 780nm. This was done by using a FORTRAN program that uses linear approximations for the RGB color coefficients.
Continuous Spectrum
Absorption Spectrum of Hydrogen

End quotation

For comparison another spectrum which approximates reality as closely as possible (source: Rendering Spectra by Andrew T. Young). Please compare especially the brightnesses at 400 nm and at 700 nm.

To visualize the spectral colours the Bruton method may be acceptable – it is a matter of taste. However, unfortunately the method has been misinterpreted as a simplified procedure for computing R,G,B-values in the general case. The following example is given to discourage from doing so.
The colours of thin films have been discussed extensively elsewhere; here they are computed using the "Bruton algorithm" (upper image) and the correct method using spectral functions (lower image). The scale gives the optical path difference of the two interfering rays in nm (nanometers).

The agreement of the latter with experiment has been shown here. One should not expect that the Bruton method yields significantly better results in other cases (glories, rainbows etc.).

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