LED color temperature

Expressed in terms of absolute temperature K, that is, a standard black body is heated. When the temperature rises to a certain level, the color starts to change from dark red to reddish-orange-white-blue, gradually changing. When the light source is the same color as the black body, we will use the black body. The absolute temperature at that time was called the color temperature of the light source.

Since the correlative color temperature is in fact a black body radiation close to the light source light color, the evaluation value of the light source light color performance is not an accurate color contrast, so the two light sources with the same color temperature value may still have a light color appearance. There are some differences. Only Feng Shuangwen can not understand the color rendering ability of the light source on the object, or how the object color is reproduced under the light source.

Corresponding color temperature of different light source environment Light source Color temperature Northern clear sky 8000-8500k

Cloudy 6500-7500k

Summer noon sunshine 5500k

Metal halide lamp 4000-4600k

Afternoon daylight 4000k

Cold camp light 4000-5000k

High pressure mercury lamp 3450-3750k

Warm camp light 2500-3000k

Halogen 3000k

Tungsten light 2700k

High pressure sodium lamp 1950-2250k

Candle light 2000k

Light source color temperature is different, light color is also different:

Color temperature below 3300K, light color reddish gives a warm feeling; there is a stable atmosphere, warm feeling;

The color temperature is in the middle of 3000--6000K. People have no obvious visual psychological effect under this tone, and there is a refreshing feeling; it is called "neutral" color temperature.

The color temperature exceeds 6000K, and the light color is blueish, giving a feeling of coolness.

a, color temperature and brightness High color temperature light source irradiation, such as the brightness is not high, then give people a chi atmosphere; low color temperature light source, the brightness is too high will give people a kind of stuffy feeling.

b. Contrast of light color In the same space, two kinds of light sources with large color difference are used, and the contrast will appear as a gradation effect. When the light color contrast is large, the light level can be obtained while obtaining the brightness level.

Using a low color temperature light source can make red more vivid;

The use of medium color temperature light source, so that blue has a cool feeling;

Use a high color temperature light source to make the object feel cold.

Color rendering:

The degree to which the light source presents itself to the color of the object is called color rendering, that is, the degree of vividness of the color; the color rendering property of the light source is indicated by the color rendering index, which indicates that the object is illuminated in light with a color that is lower than that of the reference light (sunlight) The deviation of color can more fully reflect the color characteristics of the light source. The light source with high color rendering performs better on the color, the color we see is also close to the natural color, and the light source with low color rendering performs poorly on the color, and the color deviation we see is also larger. The International Commission on Illumination (CIE) has set the color rendering index of the sun to 100 and the color rendering index of various types of light sources are different. For example, the color rendering index of high pressure sodium lamps Ra=23 and the color rendering index of fluorescent lamps Ra=60 to 90.

Color is divided into two types of faithful coloration: The ability to correctly represent the original color of a substance requires the use of a light source with a high color rendering index (Ra), and its value is close to 100, showing the best color rendering.

Effects of color: To clearly emphasize a specific color, the performance of the beauty of life can use color to enhance the color effect.

Light efficiency:

The important indicator to measure the energy saving of a light source is the luminous flux emitted by the light source divided by the power consumed by the light source. Unit: Lumens/Watts (lm/w).

Standard light source:

We know that lighting sources have a great influence on the color of objects. Different light sources have their own spectral energy distributions and colors, and the colors that appear on the surface of the object under their illumination also change. In order to unify the understanding of color, it is first necessary to specify a standard lighting source. Because the color of the light source is closely related to the color temperature of the light source, the CIE specifies the color temperature standards for the four standard illuminants:

Standard Illuminant A: represents light emitted by a full radiator at 2856K (X0 = 109.87, Y0 = 100.00, Z0 = 35.59);

Standard Illuminant B: Direct sunlight representing a correlated color temperature of approximately 4874 K (X0=99.09, Y0=100.00, Z0=85.32);

The standard illuminant C: represents the average daylight with a correlated color temperature of approximately 6774 K, and the light color approximates the sunlight of the cloudy sky (X0=98.07, Y0=100.0, Z0=118.18);

Standard Illuminant D65: Daylight representing a correlated color temperature of approximately 6504 K (X0 = 95.05, Y0 = 100.00, Z0 = 108.91); Standard Illuminant D: representing daylight other than standard Illuminant D65.

The standard illuminant specified by CIE refers to a specific spectral energy distribution and is a prescribed light source color standard. It does not have to be provided directly by a light source, nor does it necessarily be achieved with a light source. In order to fulfill the requirements of the standard lighting body as defined by the CIE, a standard light source must also be specified to achieve the spectral energy distribution required by the standard lighting body.

CIE recommends the following artificial light sources to achieve the standard lighting body regulations:

Standard light source A: An inflated spiral tungsten lamp with a color temperature of 2856K has a yellowish light color.

Standard light source B: The color temperature is 4874K, which consists of an A light source plus a cover B type DG liquid filter. Light color is equivalent to noon daylight.

Standard light source C: The color temperature is 6774K. It is composed of an A light source and a cover C-type DG liquid filter. The light color is equivalent to the sky light with clouds.

The CIE standard illuminants A, B, and C are implemented by the standard illuminants A, B, and C, but for the standard illuminant D65 that simulates typical daylight, the CIE does not currently recommend a corresponding standard illuminant. Because its spectral energy distribution can not be accurately realized by a real light source at present. At present, the development of a standard light source corresponding to the standard illumination body D65 is in progress.

The three simulated D65 artificial light sources developed today are: high-pressure xenon arc lamps with filters, incandescent lamps with filters, and fluorescent lamps. Their relative spectral power distribution matches that of the D65. The high-pressure xenon arc lamp with filter provides the best simulation. The simulation of the incandescent lamp with the filter in the ultraviolet region is not yet ideal. The simulation of the fluorescent lamp is poor. . In order to meet the needs of fine color identification production activities, there is also a mixed light source consisting of a fluorescent lamp and an incandescent lamp with a filter, which is called a D75 light source. Its color temperature can reach 7500K. Mainly used in the fine color identification work such as raw cotton.

Lab mode:

Lab mode is a relatively unfamiliar color mode. The color definition of this mode is defined by the International Commission on Illumination (CIE) and it is the mode that covers the widest range of colors in all modes. Its characteristic is that the description of color is completely mathematical, independent of system and equipment, so it can be converted between the system and the platform without deviation.

The Lab mode represents a color with a luminance component L (Lightness) ranging from 0-100; and two color components a and b. The a-component evolves from green to red - the range is -120-120; and the b-component evolves from blue to yellow - the range is -120-120.