I have a photo taken in good lighting, and I would like to show the effects of light sources with low Color Rendering Indices (CRI).

Assuming I have a complete CRI measurement of a light source (the entire set of 14 Test Color Samples, not only the first 8), how can I modify the image to simulate as best as I can the effects of a low-CRI light source?

I think I can use layers in GIMP (or equivalent software) to selectively alter the colors, one layer per patch, but what settings should I use in each layer?

Alternatively, what about simulating the effects of a light source of which I have measured the whole spectrum, instead of having only the values for the 14 TCS patches?

  • Do you have an example of what you're trying to accomplish? – Hueco Aug 31 '18 at 14:42
  • Incomplete answer, just an approach: convert all the rgb data to wavelength domain and apply a comb filter? – rackandboneman Aug 31 '18 at 16:27
  • Why not just shoot the same subject under the various types of lights? It'd be much simpler than what you're trying to do. – Michael C Aug 31 '18 at 17:49
  • I may not have personally the lightbulbs or the subject. My goal would be to show someone how a portrait or similar image would be affected or to estimate how bulbs for which I have only the CRI data would perform. – FarO Sep 1 '18 at 0:34

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