Color measurements
43
NANOCOLOR
®
UV
/
VIS
II and
NANOCOLOR
®
VIS
II V 1.1 / 10.2017
lightness (brightness). This chromaticity diagram contains (in schematic form) all visible
colors. The pure spectral colors (e.g. the color at 560 nm) are on the outer curved boundary
of the diagram. The black triangle represents schematically the color gamut of a device using
the RGB color space. As it can be observed, a monitor can display considerably fewer colors
than the human eye can see.
The point “WP” in the middle of the diagram is the so called
white point of the color scape. Each color measurement is expressed with a black cross and
corresponding title in this scheme. The user can switch between two different views of the
color charts corresponding to the mentioned norms CIE1931 and CIE1976.
Important: this diagram is very often misunderstood! It should be always remembered
that this is a very schematic representation. Of course, you can also see the colors
located outside both gamuts on a monitor or a printout. The reason is that it is
impossible to create digital pictures containing the true XYZ colors. All digital pictures
are GIF or JPG files that contain the RGB color space. If it was possible to pack the
XYZ colors in a JPG file, all colors outside of the black triangle would appear black on
the monitor! The diagram just illustrates the nature of XYZ colors that can be seen in
the real world, but cannot be displayed by a monitor.
5.6.1.1
Color references
If you regularly had to measure the color difference of a series of samples with regard to a
reference, for example compare the color of a batch with the color of a product specification,
the procedure of color comparison, described in this section, can be used. The
“color
references
” function was conceived for these kinds of applications. Measure your reference
sample and save the color values within a list of color references. The next time you want to
make a measurement with these values, you do not need to measure a reference again, but
just choose the respective color reference from a list and conduct only the measurement of
the samples. The comparison will be done automatically by the photometer.
If your color standard is defined by a reference substance and the statistical color distribution
of your samples is well known, you can create a color reference from a single measurement.
After performing the color measurement of the reference substance, press the
icon in
the color analysis menu. A screen for the definition of a new color reference will open (figure
XX). Enter an unambiguous name for the color reference and define a DE value, which
corresponds to your quality control aims. You can even enter known L*a*b* values of a color
reference manually. Confirm your entry with
. The new color reference will be
automatically stored in the database and can from now on be found in the liste of color
references in the color analysis view. A color reference can be deleted by choosing the
respective entry from the list of color references and confirming the entry “Delete current
color reference” via the
icon. Editing of color references is not possible. Therefore,
please note down the L*a*b* values of the stores color reference, in case these information
are important for the user. These values can only be viewed in the photometer, if the
corresponding color measurement is still available.
Summary of Contents for NANOCOLOR UV/VIS II
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