In terms of absolute temperature K, when a standard blackbody is heated and the temperature rises to a certain degree, the color begins to change gradually from dark red-light red-orange-white-blue. When the color of a light source is the same as that of a blackbody, the absolute temperature of the blackbody at that time is called the color temperature of the light source.
Because the correlation color temperature is actually close to the light color of the light source by blackbody radiation, the evaluation value of the light color performance of the light source is not an accurate color contrast, so the two light sources with the same color temperature may still have some differences in the appearance of the light color. Only Feng's color temperature can not understand the color rendering ability of the light source to the object, or how to reproduce the color of the object under the light source.
CORRELATIVE COLOR TEMPERATURE IN DIFFERENT LIGHT ENVIRONMENTS
Color Temperature of Light Source
8000-8500k Clear Sky in North China
Cloudy days 6500-7500k
Summer noon sunshine 5500k
Metal halide lamps 4000-4600k
4 000 K sunlight in the afternoon
Cold Camping Light 4000-5000k
High pressure mercury lamp 3450-3750k
Warm camplight 2500-3000k
Halogen lamp 3000K
Tungsten filament lamp 2700k
High pressure sodium lamp 1950-2250k
Candle light 2000K
The light source has different color temperature and color.
The color temperature is below 3300 K, and the red light gives a warm feeling, a stable atmosphere and a warm feeling.
The color temperature is in the middle of 3000 - 6000K, and there is no obvious visual and psychological effect in this tone, so it is called "neutral" color temperature.
The color temperature exceeds 6000K, and the light color is blue, giving a sense of refreshment.
A. The color temperature and brightness under the illumination of high color temperature light source, if the brightness is not high, will give people a kind of cloudy atmosphere; under the illumination of low color temperature light source, the excessive brightness will give people a feeling of stuffiness.
B. The contrast of light and color in the same space using two light sources with large color difference will produce hierarchical effect. When the contrast of light and color is large, the level of light and color can be obtained at the same time as the brightness level.
1. Light source with low color temperature can make the red more brilliant.
2. Light source of medium color temperature is used to illuminate the blue color to make it cool.
3. High color temperature light source is used to irradiate the object to make it feel cold.
The degree to which the light source presents the color of the object itself is called color rendering, that is, the degree of color fidelity. The color rendering of the light source is expressed by the color rendering index, which indicates the color deviation of the object under the light from that under the reference light (sunlight), and can reflect the color characteristics of the light source more comprehensively. The light source with high color rendering performance is better to the color, and the color we see is close to the natural color. The light source with low color rendering performance is worse to the color, and the color deviation we see is larger. CIE of the International Lighting Commission sets the color index of the sun at 100. The color index of all kinds of light sources is different, such as: high pressure sodium lamp color index Ra = 23, fluorescent lamp color index Ra = 60 ~ 90.
There are two kinds of color rendering.
Faithful colour rendering: A light source with high colour rendering index (Ra) is required to correctly represent the original colour of a substance. Its value is close to 100, and its colour rendering performance is the best.
The effect of color rendering; to highlight the specific color, the performance of beautiful life can be used to enhance the effect of color rendering.
An important index to measure the energy saving of light source is that the light flux emitted by light source is divided by the power consumed by light source. Unit: Lumen/watt (lm/w).
Standard light source:
We know that the illumination source has a great influence on the color of the object; different light sources have their own spectral energy distribution and color, and the color of the object surface under their irradiation changes accordingly.
In order to unify the understanding of color, we must first stipulate the standard lighting source; because the color of the light source is closely related to the color temperature of the light source, CIE stipulates four standard lighting body color temperature standards:
Standard illuminator A: Light emitted at 2856K by a full radiator (X0 = 109.87, Y0 = 100.00,
Z0 = 35.59;
Standard illuminator B: Direct sunlight (X0 = 99.09, Y0 = 100.00) representing the relevant color temperature of about 4874K.
Z0 = 85.32;
Standard illuminator C: represents the average sunlight with the relevant color temperature of about 6774K, and the light color is similar to that of cloudy sky (X0 = 98.07, Y0 = 100.00, Z0 = 118.18);
Standard illuminator D65: Daylight (X0 = 95.05, Y0 = 100.00) representing the relevant color temperature of about 6504K.
Z0 = 108.91;
Standard illuminator D: represents sunlight other than standard illuminator D65.
The standard illuminator stipulated by CIE refers to the specific spectral energy distribution and is the prescribed color standard of light source. It does not have to be provided directly by a light source, nor is it necessarily implemented by a light source. In order to meet the requirements of CIE standard illuminator, it is necessary to specify standard light source in order to realize the spectral energy distribution required by standard illuminator. CIE recommends the following artificial light sources to achieve the standard lighting requirements:
Standard light source A: inflatable spiral tungsten filament lamp with color temperature of 2856K has yellowish color.
Standard light source B: The color temperature is 4874 K. It is composed of A light source and cover B D-G liquid filter. Light corresponds to noon sunlight.
Standard light source C: The color temperature is 6774K. It is composed of A light source and cover C D-G liquid filter. The light color is equivalent to the sunlight transmitted from clouds.