Can you reproduce fan deck colours really precisely?

Yes – this is possible in most cases!

On the Quality of the Colour Comparison

Why not use an ICC profile conversion?

So called "ICC-profiles“, which are currently standard, are produced according to a norm of the International Color Consortium (ICC), in order to reproduce colour files on diverse output devices with colour fidelity. The procedure is perfected so that even professional users with high quality demands can adjust colourful files via ICC-profile, e.g. for the offset print (provided, of course, that high value profiles, which are accurately documented, are available).

But: Those who attempt to use an ICC profile to convert a specific RAL colour highly accurately into RGB or CMYK, will determine: the result is too impercise.

How so? An ICC profile contains about 400 and 1,500 interpolation points, in between which the comparison colours are mathematically interpolated. This is by no means enough to filter out the best fitting field from the about 20,000 CMYK colour fields within a sensible atlas.

Although the ICC process for pictures, wich contain many colours, absolutely delivers good overall results, our naked eye can often find other, better matching RGB/CMYK values for individual specific colour tones than the calculation does.

What is being calculated?

For the colour atlas we did a complete spectral photometric measurement of all of the supported colour atlases and colour systems in various colour fields and stored it as a database with about 200,000 CIELAB measurement values.

The program now searches in the comparison system for the colour which has the minimum colour distance (Delta E) to the input colour.

Is this way absolutely exact?

Yes. The progrramme will actually select the next closest colour field to the input and by no means an average value with which the eye does not agree.

Thus we reach a precision which is equal to the expert eye, only much faster. The results can be reviewed at any time via the included atlases.

The programme puts together a "detail comparison“ for reviews: The three closest colours are proposed and submitted to a comprehensive analysis.

The colour deviation Delta E

The colour atlas finds the colour tone with the smallest CIELAB colour deviation Delta E to the initial colour. The smaller the Delta E, the better the match of the two colours.

Delta E is based on the definition from the International Lighting Commission (Commission Internationale de l’Eclairage; CIE) from 1976 and is the common measure for colour variations in industrial practice. We use an advancement of the basic formula (Delta E 2000), which is even better adapted to the human perception.

In the software an evaluation of the results takes place according to the following table:

This evaluation is only approximate in nature. The eye is much more sensitive to bright, unsaturated areas than it is to dark or heavily saturated colour areas. In other words: A Delta E = 2 leads to an obviously deviating colour when dealing with a pastel colour, whereas Delta E = 2 would be barely noticeable with a dark colour tones. The eye is also more sensitive when it comes to the orange and yellow colour areas than the Delta E value initially reveals.