The effect of ink layer thickness on color rendering (3)

The color mixture matching experiment conducted by the International Commission on Illumination (CIE) showed that when the luminance ratio of the three primary colors is 1.0000:4.5907:0.0601, equal-energy white light can be matched, so CIE selects this ratio as the units of the three primary colors of red, green, and blue. The quantity is (R)+(G)+(B)=1:1:1. Although the luminance values ​​of the three primary colors are not equal at this time, the CIE regards the luminance value of each primary color as a unit. Therefore, in the color light additive method, the red, green, and blue primary light mixing ratio results in white light, and its expression is (R)+(G)+(B)=(W). Red light and green light mix to give a yellow light, that is (R) + (G) = (Y); Similarly, (R) + (B) = (M) ; (G) + (B) = (C ).

In the subtractive color method, according to the theoretical analysis, regardless of factors such as color cast, impure, etc., there are cyan, magenta, and yellow primary inks mixed in equal amounts to obtain black color, ie, (C)+(M)+( Y) = (Bk). Yellow and magenta are mixed in equal amounts to give a red color, that is (M)+(Y)=(R); the same holds true for (C)+(M)=(B); (C)+(Y)=(G). Therefore, the red colorant can be regarded as a mixture of yellow colorant and magenta colorant, that is, (R) = (M) + (Y); Similarly, the green colorant has (G) = (C) + (Y); The blue color material is (B) = (C) + (M). In this way, when analyzing the principle of color development, the color of the colorant can be represented by the primary color.

3, color color analysis

The essence of coloration of an object is that the object selectively absorbs the complementary color component of the incident light and reflects (or transmits) the remaining color light to the human eye. We know that red objects appear red when exposed to white light, that is, red objects absorb the green and blue light of the incident light (white light), and the remaining red light is reflected (or transmitted) to appear red. In order to better explain this phenomenon, it is possible to analyze the transmission condition of an ideal color filter. Assuming that a unit color of the primary color material can completely absorb 1 unit of complementary color light, and the remaining color light is completely transmitted, then 1 When a unit of white light enters a red filter of different thickness, the color rendering of the filter is shown in FIG. 3, and the expression is as follows:

11 units thick red filter: {(Y) + (M)} → pure red

21/2 units thick red filter: {1/2(Y)+1/2(M)}→1/2(R)+1/2(W) light red

With the decrease of the thickness of the red filter, the coloration has also undergone a certain change from pure red to reddish, the lightness has increased, and the saturation has sharply decreased.

Figure 3 Red material color analysis

(to be continued)