There is no black in the CRI color rendering index
The color of an object depends on the light in which you look at it, more specifically on the colors (spectrum) that make up “white” light. While the range of incandescent light bulbs only depends on their wattage, LED bulbs and other replacement bulbs require color rendering. This is done by specifying the CRI or Ra value as the color rendering index.
In accordance with DIN 6169, 14 test colors are specified. For these, one measures the secondary spectra with the reference and the test light source. The deviations give 14 reference values (Ri).
LEDs can be adjusted to a certain extent to a specific spectrum. Using several different colored LEDs makes it possible to create a light source that has a completely different spectrum than daylight but still achieves a color rendering index of 90 or more.
The number of reference colors used in the color rendering index was increased to 15. The more colors used in the calculation of the index, the more accurately the quality of the light is described. Since the different Ri values are determined as an average, even a high quality light source may display weaknesses in rendering individual colors.
In our opinion, this is especially true of black. Not a single test color is a dark color, let alone a color that is anything close to black. Therefore, based on our observation the CRI does not provide any information about how well, or more precisely how deep and color-neutral the most common color, namely black, appears on stage.
Only with the new manufacturing and color technique used in TÜCHLER lightSORBERvelours, is it possible to once again bring “good old” black back to the stage.