Question to a specialist

[lonepal]

Hi;

Does the CRI value of the light changes when we use diffuser?
What do you think?
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Regards.
Omer

[Beatsy]

Interesting question! I know diffusers *definitely* change colour temperature and different materials have different effects, but I never considered the Colour Rendering Index.

So sorry, I can't give an answer, but will watch this thread with interest...

[enricosavazzi]

Strictly speaking, the CRI is defined by the spectrum of a light source, or more precisely its R, G and B components. Whether point-like or diffused does not matter.

Having said that, anything that changes the relative amount of RGB components of the light source (including a diffuser, reflector or filter) may (and often will) change its CRI.

PS - And of course one must always remember that the CRI just expresses the distance in color space between light source RGB and Planckian locus, so you can have light sources with the same CRI that look visually very different.
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--ES