The light sources we usually refer to are generally divided into natural light sources and artificial light sources. The former mainly refers to sunlight, and the latter includes various electric light sources such as incandescent lamps, halogen tungsten lamps, fluorescent lamps, and xenon lamps. In the long-term production and life practice, people have become accustomed to identifying colors under natural light. However, due to the influence of time, climate, season, latitude and other factors, the light color of natural light is not stable. Therefore, modern industries generally tend to use Artificial light source for precise color matching. 

Our commonly used light sources are: D65, TL84, U3000, CWF, A lamp, UV lamp, fluorescent lamp, etc. Different customers use different light sources. Different light sources have different light intensities and different color rendering effects. Customers often require multiple light sources to match colors, which makes color matching more difficult. Therefore, it is necessary for technicians to understand The color rendering characteristics of the light source are necessary. 

01 The color temperature of the light source

When the color of the light emitted by the light source is the same as the color of the light radiated by the black body at a certain temperature, the temperature of the black body is called the color temperature of the light source. When a standard black body with complete absorption and radiation ability is heated, the temperature gradually increases, and the luminosity changes accordingly; the black body shows the process from red→orange-red→yellow→yellow-white→white→blue-white. The temperature at which the black body heats up to the same or close to the color light of the light source is defined as the correlated color temperature of the light source, which is called the color temperature. The bluer the light, the higher the color temperature, and the redder the lower the color temperature.

For example, the light color of incandescent lamps is warm white, and its color temperature is expressed as 2700K, while the color temperature of daylight fluorescent lamps is expressed as 6000K. 

02 The color rendering index of the light source

The color rendering ability of the light source to the object is called color rendering, which is compared with the appearance color of the object under the reference of the same color temperature or with the reference light source (incandescent lamp or painting lamp). 

There are two types of color rendering, one is faithful color rendering, and the other is effect color rendering. Faithful color rendering means that the original color of the material can be correctly expressed. It is necessary to use a light source with a high color rendering index. Use the additive color method to enhance the color rendering effect. 

Using a low color temperature light source can make red more vivid; using a medium color temperature light source, making the blue more cool; using a high color temperature light source, making the object feel cold.

03 Common light sources in the textile industry

Description of common light sources: D65, A, C, D50, D55, D75, F1, F2, F3 are often used in color measurement and matching software at home and abroad. 

CWF, WWF, TL84, U30, HOR are the commercial light sources often used internationally. 

When the relative spectral power distribution curves of some light sources are close to specific illuminants, some typical important light sources can be described by these illuminants. For example, D65 is used to represent the average sunlight, A is used to represent tungsten filament lamps, F2 is used to represent CWF, and F11 is used to represent TL84. 

Brief description of light source name

A (Incandescent) typical tungsten halogen lamp (incandescent lamp), color temperature 2856K. The main light source used in homes or shopping malls, typical incandescent lamps for metamerism testing. 

C (Sunlight) filtered tungsten halogen lamp, color temperature 6770K. The early average fluorescent lamp, but its relative spectral power distribution in the near-ultraviolet region does not conform to the average daylight, has been gradually replaced by D65. 

D65 (Daylight-Neutral) simulates the average northern sky sunlight, and is a set of relative spectral power distribution data summed up based on a large amount of data from spectral radiance measurements of sunlight at different locations on Earth. Color temperature 6500K, approximate average natural daylight, which is the average relative spectral power distribution of sunlight anywhere from 2h after sunrise to 2h before sunset, and from cloudy to clear sky light.

D50(Daylight-Red Shade) color temperature 5000KD55(Daylight-Warmer) color temperature 5500K 

D75 (Daylight-Blue Shade) color temperature 7500K 

F1-F12 (fluorescence) 12 different types of fluorescent lamps, due to the addition of fluorescent substances, compared with sunlight and tungsten filament lamps, they will show band-shaped radiation at certain wavelengths, which is a discontinuous spectrum.

CWF (Cool white fluorescence) American commercial fluorescent lamp, color temperature 4150K, typical American shopping mall and office lamp, typical fluorescent lamp for metamerism test. 

WWF (Warm white fluorescence) American commercial fluorescent lamp, color temperature 3000K, typical American shopping mall and office lamp, typical fluorescent lamp for metamerism test. 

TL84 (TL84 fluorescence) European commercial fluorescent lamp, color temperature 4100K, rare earth commercial fluorescent lamp, used in shopping malls and office lighting in Europe and the Pacific Rim, equivalent to U41 commercial fluorescent lamp in the United States.

U30 (Ultralume 3000 fluorescence) American commercial fluorescent lamp, color temperature 3000K, rare earth commercial fluorescent lamp, used for shopping mall lighting, equivalent to European commercial fluorescent lamp TL83. 

HOR (Horizon) tungsten halogen lamp (incandescent lamp), color temperature 2300K, simulates the rising of the sun in the morning and the sunlight of sunset in the afternoon. It belongs to the light source used in households or shopping malls with A. Metamerism test lamp, commonly known as dusk fluorescent lamp. 

ps: 

"Jumping light" is a common name for the phenomenon of metamerism in dyeing factories, that is, two colors have the same color under a certain light source, but the color is inconsistent when another light source is changed. 

Normally , we will communicated with client to confirm the light sources standard when lab dip process .