Colour Difference
How different are two colours?In this window any two colours can be compared to each other in detail. The colours are displayed as a screen preview and varying colour distance measures (Delta E) are specified.
The Window Colour Difference
Brief Instruction
- Select a colour in the left area.
- Select a colour in the right area.
- The colour difference of the selected colours is outputted according to CIE-formula from 976, 1994 and 2000 and the CMC-l:c-Formel.
- You can change the size of the window with the 4-arrows-button.
Delta E
The numerals in the subscript indicate the belonging (original colour or comparison colour).
You can see further calculation fundamentals in our small formulary.
CIE 1976
Delta E of 1976 is nothing else than the spatial distance between two points in the L * a * b * color space.
Even though this formula is still the most widespread colour distance measure in the laboratory practice, it has its weaknesses. It weights colour hue differences as heavily as brightness or saturation difference in evaluation, even though the eye finds the latter two much more agreeable. Through modifications to this formula attempts are being made to approximate a visual equidistance in the dipicition.
CMC
The "Colour Measurement Committee" of the "Society of Dyers and Colourists" published their formula in 1984.
It contained the following, mostly relevant for the textile industry, correction factors:
- More heavily weighted lightness when dealing with very dark colours (SL)
- More heavily weighted saturation when dealing with very achromatic colours (SC)
- Correction of the hue in connection with the saturation (SH)
- Correction of the lightness (l)
- Correction of the saturation (c)
The parameters l (lightness) and c (chroma) are varied depending on each application. The combination CMC (2:1) is established in the textile industry. In non-textile work environments l = 1.3 or 1 is preferred, which means a smaller absorption of the lightness.
Coat of Paint | Textile | |
---|---|---|
kL | 1 | 2 |
kC | 1 | 1 |
kH | 1 | 1 |
k1 | 0,045 | 0,048 |
k2 | 0,015 | 0,014 |
CIE 2000
The CIEDE2000-formula is, through the influence of newer data sets, and compared to the little accepted CIE94-formula and also the CMCl:c, to achieve a refinement of the results.
Five correction factors were implemented:
- A hue rotation value (RT), in order to correct blue hues around 275°
- Compensation for neutral colours
- Compensation for lightness (SL)
- Compensation for saturation (SC)
- Compensation for hue (SH)