Colour Values

Which RGB-/CMYK-/LAB-/HLC– colour value has a certain colour?

In this window the colour values of all important colour systems are displayed in various models. This way the values can be used in all colour capable programs with the colours, whether RGB, CMYK or HLC input is used. The final quality, i.e. the agreement with the original colours, is also shown.

The most important colour values at a glance.

Brief Instuction

  1. Select a given colour system and the wanted colour.
  2. The colour values in Lab, HLC, RGB, HEX and CMYK are displayed in the right area.
  3. Using the buttons bottom right the colour values can be exported into the clipboard and then displayed in the 3D colour space or saved as a PDF-document.

La*b* and HLC Values

The colour values of the CIELAB-model are device-independent and represent the base values of the software, in which the colour is defined (the appearance of a RGB– colour value depends on the output device).

A good output quality can be achieved within programs with colour management functionality by direct input of the Lab values (if also a high-quality profile file for the concerned output device is present). Programs in which a free input of Lab-colour values is possible, are for example Adobe Photoshop, PageMaker or the Corel Graphics Suite.

HLC colour values are a simple conversion of the cartesian coordinates L, a and b into polar coordinates Hue, Lightness and Chroma. The HLC colour values are intuitively conceivable.

RGB Values

The RGB values are based on a conversion of the Lab values in Standard-RGB (sRGB).

The RGB-standardisation "sRGB" was released in 2000 by HP and Microsoft in order to counteract the chaos of different RGB-displays on different output devices. Today many printers, plotters and monitors are adjusted to the sRGB-standard. The sRGB-preparation of the colours is therefore especially important. It guarantees, to some extent as the least common denominator, a good reproduction of the colours on different printers and monitors.

sRGB should be used for applications on the screen and at colour printers of all types.

Optimisation Procedure, Parameter
sRGB software supported Lab/RGB conversion
ICC-Profil sRGB Color Space Profile.icm
Trinitron software supported Lab/RGB conversion
ICC-Profil: AppleRGB.ICC

CMYK Values

The values of the nearest colour [type] of the corresponding atlas are shown. (Identical CMYK values are presented as first solution in the window "Next Colours" when choosing the corresponding CMYK-atlas.

Optimisation Procedure, Parameter
Art print matte coated, coated woodfree, white, woodfree
Schneidersöhne LuxoArt Silk 170 g/m² (ECI type of paper 2; the result of the print is according to ECI/FOGRA also usable as reference for the paper class 1 (glossy coated)
raster frequency: 175 lpi; 70er raster
Naturpapier uncoated Offsetprintpaper, white
Munken Lynx 200 g/m²; 1,13 vol. (ECI type of paper 4)
raster frequency: 138 lpi, 54er raster
Newsprint (Recycling) uncoated Offsetprintpaper, white
Recystar 150 g/m²; 1,3 vol. (ECI type of paper 4)
raster frequency: 138 lpi, 54er raster

Quality of the Colour Values

The CMYK colour values in the DIGITAL COLOUR ATLAS do not base on the ICC profile conversion. Instead of this they are based on the initial measurment of all colour types of the printed atlases and subsequent DeltaE-minimization. There are approximately 6,000 interpolation points compared with 1,400 for a CMYK profile.

Also the CMYK preview is not based on a calculated conversion of the CMYK values in RGB by using an ICC profile, but for this the therefore measures LAB colour values of the corresponding CMYK colour field are readout from the data base and converted to RGB – even here there is a quantitative advantage due to the plural of the interpolation points and due to the direct measurment of all fields.

The RGB values for a colour are generated by using the common LAB->sRGB algorithmen.

Conclusion: The CMYK colour values and previews are with their exactness better than the correpsonding informations for a colour e. g. in Photoshop, InDesign, QuarkXprress etc. . The CMYK preview fields show a more detailed picture of the result of the print as the mentioned applications. The sRGB-values are equally exact like in the mentioned applications.