Why is it different to look in the mirror under different light?

But the main cause of visual error is the physiological decision of human eyes.

◆ Color perception elements

Visual color perception caused by objects is determined by the following three factors:

(l) The property that the surface of an object reflects the illumination light to the main room is determined by the chemical structure and composition of the surface and the physical and geometric characteristics of the surface.

(2) The nature of the lighting source, that is, the wavelength composition characteristics of the light source-the energy distribution of light energy in the relevant visual band range, that is, its color temperature in terms of the chromaticity quality of the light source.

(3) The color sensitivity of eyes is mainly determined by the ability of the optic nerve system on the retina to perceive light and the ability to process and transmit light stimuli.

◆ Three elements of color vision

1. Tone Tone is one of the most basic sensory attributes of color, which enables us to distinguish different parts of the spectrum. That is, chromatographic segments are distinguished according to the color senses of red, orange, yellow, green, cyan, blue and purple. Without this visual attribute, there would be no color, just like the world of panchromatic blind people. According to the colorless phase property, the color perception caused by the outside world can be divided into two systems: colored system and colorless system.

(1) Having a color system means having a color vision of the same hue. Only the color system has three measures: hue, saturation and lightness.

(2) achromatic color color system refers to color vision without hue attribute. Achromatic system has only one measure of lightness, and its saturation is equal to zero.

2. Saturation Saturation is a visual attribute, which enables us to judge the vividness of vision with hue attribute. There is a color system whose brightness is directly proportional to saturation, according to people's experience in using pigment substances. The higher the pigment concentration, the brighter the color and the higher the saturation. Words describing the degree of saturation are thick, light, deep and shallow. Achromatic color color system is a state with saturation equal to zero, just like we gradually fade the color on the color display, and finally become a black-and-white picture.

Physiological research shows that human eyes have different feelings about color saturation. Eyes are strongly stimulated by red light, weakly stimulated by green light and have low saturation. So, China is full of red taxis. From the perspective of visual science, it is actually a kind of visual pollution. Nobody likes to stare at a red taxi for a long time. So much red will cause restless emotions. Drivers choose red for two reasons. One is that red-envelope cars are cheap (red dyes are easy to buy), and the other is that China people like red Geely. In fact, it is really a misunderstanding of spreading information from one source to another, which has no scientific reason.

3. Brightness Brightness is a visual attribute, which enables us to distinguish the bright and dark levels of achromatic perception. This degree of brightness depends on the intensity of brightness, that is, the level of light stimulation energy. Please note: don't misunderstand this definition, that is, there is no lightness attribute without color system. It only emphasizes that the visual attribute of lightness is an exclusive hue attribute, which only involves the feeling of light and dark levels, just like taking a photo with black and white panchromatic film only records the light and dark levels without recording the hue. According to the intensity of brightness perception, it can be divided into three levels from the brightest to the darkest: white-colorless perception at the high brightness end; Achromatic width of black-low lightness end; Gray-a medium brightness between white and black. Sketches and uncolored sculptures in painting use this lightness to express artistic themes.

Scientific research has found that as the light darkens, the level of light and shade in our eyes will become dim sharply. When the light is weak, we can hardly distinguish between clarity and darkness. Also under strong light, the eyes will become dull to the light and shade levels. The study also found that the human eye is most sensitive to the yellow-green part of 555 nm. Therefore, from the ability to impress perception. The yellowish green light is the most eye-catching. Also found. The spectral sensitivity of human eyes also depends on the brightness level. At low brightness level, the spectral agility curve will shift to short wave direction. Make human eyes relatively more sensitive to the colors of short wave series. This makes the outdoor scenery turn blue before dawn and after sunset, and the blue-purple flowers or objects become noticeable. Night is always a blue scene, that's why. This provides a scientific reference for us to design outdoor advertisements. We can design and choose eye-catching colors according to the sunshine characteristics and different environments in different places, and at the same time choose the appropriate light intensity according to the area and height of advertisements.

◆ Visual adaptation effect

Visual adaptation mainly includes three aspects: distance adaptation, light and shade adaptation and color adaptation.

Length-distance adaptation The human eye can recognize the shape and color of a certain area. This is mainly based on the adaptive function of visual physiological mechanism to adjust the distance. The lens in the eye structure is equivalent to the lens in the camera, and the focal length can be adjusted. Because the lens can automatically change its thickness, the image can be accurately projected onto the retina. In this way, people can adjust the focal length by changing the shape of the lens, so that they can