Friday, February 1, 2013

New CMFs and More Accurate Spectrum Renders

I updated the color matching functions (CMFs) that my spectral rendering system uses to convert spectral power distributions to CIE XYZ. My new CMFs are the new, physiologically-relevant, 2-deg XYZ CMFs transformed from the CIE (2006) 2-deg LMS cone fundamentals. My old ones were the CIE 1931 2-deg, XYZ CMFs modified by Judd (1951) and Vos (1978).

I made some new images of the visible spectrum rendered into the sRGB color space. When you convert XYZ to sRGB you get negative color components when the color lies outside the sRGB gamut. Clipping these negative components to zero distorts the color. But if you add white light to the entire spectrum, you can bring the negative components into the displayable range, resulting in an accurate picture of what the spectrum looks like on a gray background. In each gray background image below, I added just enough white light to bring the most negative value to zero, and I set the range so that the most positive value maps to one. In each of the darker, black background images, I simply removed the white light. And in each of the brighter, black background images, I brightened the spectra just enough to utilize the entire displayable range.

New spectrum on gray.
Wavelength range: 390–830 nm.

New spectrum on black.
Wavelength range: 390–830 nm.

New spectrum on black, brightened.
Wavelength range: 390–830 nm.




New (top) and old (bottom) spectra on gray.
Wavelength range: 380–830 nm.

New (top) and old (bottom) spectra on black.
Wavelength range: 380–830 nm.

New (top) and old (bottom) spectra on black, brightened.
Wavelength range: 380–830 nm.




Old spectrum on gray.
Wavelength range: 380–825 nm.

Old spectrum on black.
Wavelength range: 380–825 nm.

Old spectrum on black, brightened.
Wavelength range: 380–825 nm.

1 comment:

  1. The effects you have given in the background has given brighter colors to the spectrum. The one with black background has made the colors more prominent.

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