Color rendition is the term used to describe the degree to which an object or surface color (walls, ceiling, furniture, workpiece) seems "normal" when viewed under artificial light. It is an important quality criterion. The concept of color rendition is based on the assumption that an object color appears normal when illuminated by a thermal radiator or daylight (High Color Temperature).
The general color rendering index (Ra) expresses the sum of the differences measured for various test colors when comparing a given illuminant with a reference light source . A simple overview is available in the form of color rendition classes for light sources pursuant to EN 12464, Part 1.
Various levels of color rendition are prescribed in the standards (e.g. EN 12464, Part 2) depending on the type of the interior and the activities involved. In general, Color Rendition Class 1A indicates the best possible quality of color rendition, as required for color testing and monitoring, for example, as well as in critical areas in hospitals and clinics. For office interiors Class 2A is normally adequate.
The general color rendering index (Ra) expresses the sum of the differences measured for various test colors when comparing a given illuminant with a reference light source . A simple overview is available in the form of color rendition classes for light sources pursuant to EN 12464, Part 1.
Color rendition classes
The standard defines six color rendition classes, which can be matched with the general color rendering index as follows:
|
Classification |
Color Rendition Class |
Color Rendering Index Ra |
|
very good |
1A |
Ra ≥ 90 |
|
|
1B |
80 ≤ Ra < 90 |
|
good |
2A |
70 ≤ Ra < 80 |
|
|
2B |
60 ≤ Ra < 70 |
|
not so good |
3 |
40 ≤ Ra < 60 |
|
|
4 |
20 ≤ Ra < 40 |
Various levels of color rendition are prescribed in the standards (e.g. EN 12464, Part 2) depending on the type of the interior and the activities involved. In general, Color Rendition Class 1A indicates the best possible quality of color rendition, as required for color testing and monitoring, for example, as well as in critical areas in hospitals and clinics. For office interiors Class 2A is normally adequate.
Quality of color rendition
|
Color rendition class |
very good |
good |
not so good |
|
|
|
|
Color rendering index Ra |
Ra ≥ 90 |
80 ≤ Ra < 90 |
70 ≤ Ra < 80 |
60 ≤ Ra < 70 |
40 ≤ Ra < 60 |
20 ≤ Ra < 40 |
|
Incandescent lamps |
X |
X |
|
|
|
|
|
Compact- |
X |
X |
|
|
|
|
|
Fluorescent lamps |
X |
X |
X |
X |
X |
|
|
High-pressure mercury lamps |
|
|
|
X |
X |
X |
|
Halogen- |
X |
X |
X |
X |
|
|