Principle Of User Calibration - Minolta CA-100Plus Instruction Manual

3. Principle of User Calibration

This instrument uses three detectors provided in the measuring probe's receptor to measure the colors of the
display.
The spectral sensitivity of these detectors does not match that of CIE 1931 color-matching function perfectly.
Because of this, some colors of the display are affected by slightly shifted spectral sensitivity, resulting in the
situation that absolute values of the measured values differ from the values (true values) obtained when the CIE
1931 color-matching function is used.
This instrument allows one of the user calibration methods; white calibration (single-color calibration) or matrix
calibration (RGB+W calibration). By performing user calibration, the influences that occur due to slight differ-
ences between the spectral sensitivity of the detectors used in the instrument and that of CIE 1931 color-matching
function can be corrected when measurement is performed.
These user calibration methods have the following features, so the user calibration that best suits your application
must be selected.
White Calibration
User's own correction factor is set to the memory channels by measuring the white color of known values and
setting the obtained calibration values (xyLv) to the instrument. Once this factor is set, the measured values will be
displayed after correction by this factor and output each time measurement is taken.
Performing user calibration provides higher accuracy for measurement of colors that are close to the white color.
Matrix Calibration
User's own matrix correction factor is set to the memory channels by measuring three monochrome colors (R, G
and B) of known values and setting the obtained calibration values (xyLv) and emission characteristic to the
instrument. Once this factor is set, the measured values will be displayed after correction by this factor and output
each time measurement is taken.
Performing matrix calibration enables high-accuracy measurements of LCD displays that provide colors through
additive color mixing of three monochrome colors (R, G and B).
Since the matrix correction factor obtained from Minolta's calibration standard has been set, measured values
calculated based on this factor will be acquired when this instrument is used for the first time since shipment from
the factory.
Correction of Reading Differences between Instruments using User Calibration
(When two or more instruments are used or when the optional 4-point expansion board CA-B04 is used to use two
or more measuring probes)
Some measuring probes may have a slightly different spectral sensitivity. As a result, even if you are measuring the
same display, measured values may differ from one instrument to another (difference of readings between instru-
ments).
Such influences can be corrected by performing user calibration using the same display and the same calibration
values.
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