Introduction and applications of common standard light sources
1. D65 light source
D65 is a white light source similar to midday sunlight. Its color temperature is 6500K and is considered one of the standards for natural white light sources. In many applications, D65 is often used as a reference light source because it provides a relatively balanced color distribution, and colors from warm to cool colors can be accurately represented. The color temperature and spectral distribution of D65 are well suited for many applications.
2. D50 light source
D50 is a white light source similar to daylight with a color temperature of 5000K. It is usually used as a standard light source for image processing and printing. It offers fewer yellow and blue tones than the D65, so in some areas, such as design and printing, using the D50 will produce a more accurate color match.
3. TL84 light source
The TL84 light source is a blue-toned light source similar to daylight with a color temperature of 4000K. It is mainly used to evaluate and compare the color of materials such as textiles, leather, and plastics. It displays blue and white colors accurately, while other colors are slightly offset. Therefore, the TL84 is often used where blue and white colors need to be evaluated with emphasis, for example in the textile industry.
4. CWF light source
CWF light source is a white light source similar to sunlight with a color temperature of 4150K. It is mainly used to evaluate and compare the color of printed matter and certain chemicals. It displays yellow and green colors accurately, while other colors are slightly offset. Therefore, CWF is often used where yellow and green colors need to be evaluated with emphasis, for example in the printing industry.
5. A light source
A light source is a warm white light source similar to night light with a color temperature of 2856K. It is mainly used to evaluate and compare the color of indoor lighting, lamps and some low-temperature lighting devices. It displays warm colors accurately, while other colors are slightly offset. Therefore, A light sources are often used where warm colors need to be evaluated with emphasis, such as in the indoor lighting industry.
6. F light source
F light source is a white light source similar to daylight, but it has a higher blue light component than CWF and D65. It is mainly used to evaluate and compare the color of medical equipment and dental materials. It displays blue and white colors accurately, while other colors are slightly offset. Therefore, F light sources are often used where blue and white colors need to be evaluated with emphasis, for example in the dental materials industry.
7. Special light sources
U30, U35, UV, INCA, etc. are special light sources. They are usually used in specific applications, such as detecting and evaluating the fluorescence properties and reflectivity of materials.
U30 and U35 light sources are commonly used to detect and evaluate the fluorescent properties of materials, such as fluorescent dyes, optical brighteners, etc. The spectra of U30 and U35 are distributed in the ultraviolet region, with ultraviolet components with wavelengths of 300nm and 350nm respectively. The difference between U30 and U35 lies in the different proportions of ultraviolet components. U30 has a higher ultraviolet component and is suitable for detecting relatively weak fluorescence signals, while U35 has a lower ultraviolet component and is suitable for detecting relatively strong fluorescence signals.
UV light sources are often used to evaluate the response of materials to ultraviolet light, such as evaluating the durability and stability of paper. The spectral distribution of UV light source is mainly in the ultraviolet region, usually ultraviolet light with a wavelength of 365nm.
The INCA light source is a special light source commonly used to evaluate the color and reflectivity of materials, such as paint, plastic, glass, etc. The spectral distribution of the INCA light source is similar to daylight, but it has higher brightness and color temperature, and can accurately display high reflectivity and high saturation colors.
It should be noted that these light sources have special spectral distributions and uses and cannot replace conventional standard light sources for color comparison and evaluation. When using, appropriate light sources should be selected according to actual needs.
The role of standard light sources in ISP processing
Computer image processing is an integral part of modern computer science and involves extracting features from raw image data and processing and analyzing them. In this process, the selection and control of light sources is very important, because different light sources will affect the color and brightness of the image. Therefore, it is very important to use standard light sources for computer image processing.
The main role of the standard light source in ISP image processing is to correct the color temperature and white balance of the image. White balance refers to the different color deviations of the light received by the camera sensor under different light sources, so the color of the image needs to be corrected according to the environment. A standard light source can provide a known color temperature and color space, and by comparison with the light received by the sensor, the color of the image can be corrected and chromatic aberration eliminated.