User Calibration - Konica Minolta CR-400 Instruction Manual

User Calibration

It is extremely difficult to perfectly match the spectral response three photoelectric tristimulus colo-
rimeters like this instrument to the CIE 1931 standard observer, creating a slight discrepancy in spec-
tral response. (See Figure.)
In color difference measurement, the effects of this slight discrepancy in spectral response is within
the scope of measurement accuracy, so it does not present a problem. However, in color measurement,
depending on the color of the specimen to be measured, there are times when a slight discrepancy with
the value (true value) gotten when measuring using an ideal prism response. There might even appear
a similar discrepancy in spectral response when performing measurements using two of the same
model instrument, creating discrepancies in the assigned values when using multiple instruments.
CIE 1931 colorimetric standard Observer curves and spectral response of KONICA MINOLTA chroma meter
When this happens, it is possible to minimize the discrepancy in assigned value by using the user
calibration function.
The user calibration is set by measuring a target specimen with a known sensitivity ahead of time and
setting this value as a calibration target color in a calibration channel (ch 01-19). This calibration data
is then used to correct the assigned value when measuring
Thereby almost the discrepancy eliminates completely in the assigned value when measuring a color
close to the target specimen color. This also applies to colors which are far from the target specimen
color.
There are two ways of user calibration: the multi-calibration function and the manual select calibration
function. Choose whichever is most appropriate for the number or type of colors to be measured.
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Spectral response of KONICA
MINOLTA chroma meter
CIE 1931
Wavelength (nm)