QUANTIFYING THE BASIC COLORS OF COLORIMETRIC COLOR DESCRIPTION MODELS

At present, the quality of multi-color prints can be assessed both
visually and using densitometry control, i.e. quantitatively. It would be impossible to
imagine the quality of color reproduction without methods of precise color description in
standardized mathematical expressions. In practice and scientific researches two ways
of systematization and quantitative description of colors are applied. The first is the
color standards method, and the second is the measurement method, or colorimetric
method. In the color standards method, sets of colors are prepared in advance. The
colorimetric method is based on the fact that each color has three quite defined values -
the color coordinates. Color models of color description are a means of quantifying color and the differences between shades of color. There are four types of color description
models. Two models are the most commonly used in practice: additive RGB, and
subtractive SMUK. The RGB model takes red, green and blue as the primary or basic
color. In the subtractive RGB model, cyan, magenta, and yellow are chosen as the
primary colors. The purpose of this paper is to quantitatively evaluate the RGB and
subtractive RGB color models. The base emissivity of both colorimetric systems were
evaluated on a spectrophotometer CM 3600d. The spectral reflectance curves of the
primary colors of the subtractive SMUK were evaluated. Color equations for both
mathematical models have been compiled using the reflection coefficients; color
envelopes have been studied using the chromaticity diagram. It has been found that
additive RGB model has greater color gamut than subtractive SMUK model, i.e. color
losses occur. Therefore, scanners and digital cameras, monitors and output devices
should be calibrated during reproduction.