The quality of light is an important indicator for lamps that are used in everyday life. It includes many characteristics.
Photo: Vistosi.
Such characteristics such as constancy, saturation and color accuracy include both painted and white light. The two main characteristics of the quality of white light are the color temperature and color rendering index.
The color rendition index shows how well the light source transmits the colors of the illuminated objects. It reflects the ability of the light source correctly transfer the colors of various objects in comparison with the perfect light source. This parameter is a quantitative indicator of the quality of color shades on a scale of 0 to 100. By definition, the color reproduction index of sunlight or lighting the incandescent lamps is 100. The maximum similarity of the reproducible colors relative to the reference light source also corresponds to the index value of 100.
Photo: Philips.
In practice, a test is used to measure how the colors of eight standard color samples designated, change when illuminated by the light source relative to the illumination of the reference light source. The colors of eight samples have relatively low saturation and are evenly distributed over the entire tone range.
The minimum acceptable value of the light source color reproduction index depends on the field of its application:
- The value of the color reproduction index in the range of 90-100 is required in places in which the exact color rendition is critical - for example, in the art gallery.
- For most residential premises, the color rendition index must be no less than 70-90.
The color rendering index is indicated on the lamp packaging.
Color temperature shows how white color is perceived: warm (reddish), neutral or cold (bluish). It is measured in degrees of Kelvin (K), in which absolute temperature is usually measured. With increasing the temperature of the black body, the color of the light emission emitted by them changes as follows: Red - orange - yellow - white - blue. It resembles a piece of iron that heats up in blacksmith mountain.
Photo: pexels.
The incandescent lamp emits the light with a color temperature of approximately 2700 k, which is in a warm or reddish area of the color space. Since in the incandescent lamp, the thread is used, which is heated when light radiation, the thread temperature is also the color temperature of the light radiation.
Specific color temperatures corresponding to the light from warm to cold are associated with certain light sources and a decor. The color temperature also affects the emotional effects of space and can strongly change the appearance of the items.