Beg. What is the relationship between gouache, color transparency and light and dark parts?

Color transparency: the color with weak concealment, such as lemon yellow, the more water the pigment is mixed with, the thinner the pigment is, and the more transparent it is displayed on the screen. Gouache pigment has strong hiding power. Generally, the transparency of the bright side is much lower than that of the dark side. For example, when drawing apples, the bright colors are generally stronger than the dark ones. It is also because white will be added to the bright surface, and white has the strongest hiding power. Although black has a strong hiding power, black pigment should be used with caution when painting gouache.

The relationship between the bright part and the dark part: the bright part is affected by the direct illumination of the skylight (the skylight is cold in normal weather with blue sky and white clouds, and it will get warmer in the evening and morning), so the bright part is cold. According to the relationship between cool color and warm color, the dark side will appear as a relatively warm color visually.

Between the bright surface and the dark surface, it is divided into highlights, bright gray surfaces, light-dark dividing lines, dark gray surfaces and reflective surfaces. Cobalt blue should be added to the highlights. The bright gray surface shows the inherent color of the object because it has not been changed by direct light. The boundary between light and shade is not affected by direct light, ambient light and color, so it appears in the darkest part. The dark gray surface is on the dark side, which is gradually brightened by the influence of ambient light and color, and the brightness is second only to the dividing line between light and dark. The reflecting surface is transmitted by the light energy of the surrounding objects, so it is the brighter part of the dark tone and will receive the light and color of the surrounding objects.

For example, draw a red apple, bright red is relatively cold red, add a small amount of blue, and the transition to bright gray is the inherent color system of the apple. At the boundary between light and dark, red and dark blue gray become dark gray red, but the red display is extremely weak. From excessive to dark gray tone, the red system gradually increases, and the red gradually increases. It should be noted that if the apple is placed on a yellow cloth, the brightness of this cloth is higher than that of the apple itself, then the dark reflective tone will receive the light energy transmission of the yellow cloth and become bright and discolored, and a small amount of yellow will be added to the pigment to draw a dark gray surface.

Shadows and main colors are the inherent colors of yellow cloth. According to the relationship between cold and warm colors, the warm color of the shadow relative to the dark side of the apple will give people a cold feeling. From the place where the apple touches the yellow cloth, the color changes from dark to bright. The transition from warm to cold.

In color, the relationship between cold and warm is relative, even if the shadows are the same, there will be a gradual change in hue brightness and cold and warm.

Therefore, when painting colors, we should pay attention to the changes of hue purity, lightness and warmth, especially local changes. Only in this way can colors be more expressive.