Color Measurement Knowledge for You

There was once a commercial that said, "Without the sound, the best play can't come out." It is the perfect combination of sound and image that creates a complete film and television production. Well, color in the big wide world is really too important. Color is a psychophysical quantity. Color is perceived by the human eye as a light signal reflected or transmitted by an object. What do you know about color?

I. Properties of Colors

The three elements of color are luminosity, hue, and color saturation. 

In the LCH color space, L is luminance, C is saturation, and H is hue.

In the RGB color space, R is red, G is green, and B is blue.

In the LAB color space, L stands for brightness; a stands for red-green bias, where a is positive for red and negative for green; b stands for yellow-blue bias, where b is positive for yellow and negative for blue.

II. What happens when light is incident on an object's surface

1. The main cause of surface gloss is the specular reflection that occurs on the surface of the object. 

2. When light incident to the interior of the object, scattering occurs within the object, resulting in a diffuse reflection and diffuse transmission.

3. Diffuse reflection and diffuse transmission of light propagated in the object, different wavelengths of light will produce different absorption, resulting in a different color than the incident light.

4. When the object is more transparent, part of the light will be directly through the object, resulting in transmission.

The color of a light source is determined by the spectral distribution of the light source. The color of an object is determined by the spectral properties of its surface. The direction of light reflected from a mirror depends on the smoothness of the surface of the object. Depending on the roughness of the surface, the spatial distribution of the reflected light from the mirror will vary.

Therefore, the colorimeter measurement modes for color spectra are also divided into SCI and SCE modes. SCI refers to a method that includes the specular reflection of light and is generally used by manufacturers, such as paint and coatings companies, who study the properties of the color itself and are not concerned with the glossiness of the sample to which the color is attached. SCE refers to a method that does not include specular reflection and is generally used for samples that are directly observable and require measurements that are very close to the eye, such as appliance housings. The spectrophotometer series is compatible with SCI and SCE modes for a wider range of applications and more accurate measurements.