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LabSpion user guide
CRI details
The CRI describes the quality of white light also known as
the Color Rendering Index or Ra. The value describes how
full the spectra is, thus how good the light is to reflect colors
of an object being illuminated.
The CRI is calculated using test colors to test chromatic
adaptation of the light according to the test colors.
The test colors consist of 15 test colors but only the first 8
known as R1-R8 is used to calculated the CRI, the
remaining R9-R15 are not used. But LED lights can in some
cases be missing the red light component contained in R9
which is not included in the CRI measurement therefore has
it been common to measure the R9 component as well.
R9-R15 values can be view by opening the CRI details
window by clicking on the CRI bar or selecting View->CRI
details.
We can see from the CRI details above that the level of red
light R9 is quite low compared to the rest. R9 can in some
cases become negative due to very low levels of red light.
