Color depth (colorant)
Color depth is a measure of the intensity of color perception , which increases with increasing saturation and generally decreases with increasing brightness .
Basics
definition
Coloring of two colorants with the same depth of color looks as if the underlying pigments or dyes had been used in the same concentration . In reality, however, the color strengths can differ so that a different concentration is necessary to achieve the same color depth.
The following table makes this difference clear:
| example | Concentration pigment 1 | presentation | Concentration pigment 2 | presentation |
|---|---|---|---|---|
| Same concentration | 1 % | 1 % | ||
| Same color depth | 1 % | 2% |
Explanation: Pigment 2 has only half the color strength compared to pigment 1 (first line). The same depth of color can be achieved by doubling the concentration (second line).
attitude
Bleed colorations of the to be tested colorant in combination with a white pigment, the concentration of the non-ferrous pigment to the desired color depth by adjusting set .
The pigment concentration required to achieve a certain depth of color therefore depends on the paint system used.
The same color depths are absolutely necessary for the visual comparison of pigments; otherwise the influence of the color strength cannot be eliminated, which can lead to errors in the evaluation. Such a color strength adjustment is particularly important when adjusting products during pigment production .
Representation in the color space
Converted to the coordinates of the CIE-L * a * b * color space , samples of the same color depth represent approximately the outer surface of a cone that opens upwards. This means that the following relationships are mandatory:
- There is a lower limit for the brightness L *, which corresponds to the theoretical setting from ideal black to standard color depth (see below). Therefore, there are no colorations with lower brightness adjusted to the respective color depth.
- With the same hue angle, lighter colors of the same depth of color are also purer in color than darker colors.
Color locations of real pigments
Pigments in the green , blue and violet range absorb a larger part of the visible spectrum and therefore appear in principle darker than yellow , orange and red pigments. When set to the standard color depth, these also result in comparatively cloudy color tones.
Inorganic pigments are mostly more cloudy than organic pigments. Colorings with standard color depth are therefore also darker.
The brown and ruby color ranges are an exception : pure and at the same time dark organic pigments are required here. These also tend to appear more cloudy and darker than the classic light and pure pigments.
Standard color depth
history
Various standard color depths have been specified in normative terms. Initially, reference colors set visually by colorists were used. At that time, the setting was also exclusively visual.
In the meantime these have been replaced by tables of values . According to DIN , up to thirteen different formulas are available for a combination of standard color depth / type of light, depending on the angle .
calculation
In principle, each hue angle h in the CIE XYZ color space is assigned a point with a defined color distance to the white point (also: achromatic point ). This distance depends on the brightness Y in this color space, the standard color depth to be achieved and the type of light used. When setting to standard color depth, the color distance (here: B) is calculated to the point defined above with the same hue angle. When this is equal to zero (in practice: close to zero), the standard color depth is considered to have been reached.
Nowadays these formulas are usually stored in the colorimetric software so that the setting to the standard color depth can be made in a simple manner.
Important standard color depths
The most important specified standard color depths are shown in the table.
| Standard color depth (ST) | description |
|---|---|
| 1/1 | Close to full tone |
| 1/3 | , Low tone in older sample cards as color depth I called |
| 1/9 | Bass |
| 1/25 | , Slight improvement in older sample cards as color depth II referred |
| 1/100 | Lightening |
| 1/200 | , Strong brightening in older sample cards as color depth III referred |
Depending on the application, different color depths are important:
- for automotive and industrial paints, it is traditionally more relevant to use lower tones
- For building colors, the strong white lightening ( pastel tones) are more important.
In pigment sample cards you will therefore usually find 1/3 ST and 1/25 ST as well as a full-tone coloration. The latter is produced without the addition of white pigment and therefore does not correspond to any defined standard color depth.
Individual evidence
- ↑ a b DIN 53235-1 . In: German Institute for Standardization e. V. (Ed.): Colorants 1 . 7th edition. DIN-Taschenbuch 49.Berlin, Vienna, Zurich 2012, ISBN 978-3-410-23202-5 , pp. 182, 190 .