In colour matching tests on colours containing a high fraction of interference pigments with high colour-travel, a measurering geometrie was identified which allows the colour changes wich lie outside the measuring range of conventionell commercially avaiable colour measuring systems to be measured. It is assumed that these types of pigments, which are supplied by leading pigment manufacturers (MERCK, BASF, FLEX-PRODUCTS, ENGELHARDT), will be increasingly used in the future in series car production. These pigments have already been used for a number of years for same series production colours. The measuring geometry developed in this project also enables the colouristic properties of these pigments to be fully analysed and characterised. This hence represents a significant advance compared to the current state-of-the-art. Based on this geometry, ColorAIXperts constructed a prototype of a colour measuring instrument based on the multispectral method and tested and optimised its functions. In order to investigate the use of this measuring system for car paints and to validate the results for the user group, 47 colours were selected which covered the whole relevant colour space and which also had representative optical properties for car paints such as gloss, coarseness/fineness of the effect, etc. A portion of the colours were colours in the current colour ranges of car manufacturers, the rest were colours prepared at IFAM to cover the colour regions not covered by current colour ranges for purely aesthetic reasons (violet, purpie, magenta, bright yellow, bright orange). For each colour, a standard sheet and four sample sheets were defined. The sample sheets were each measured and matched against the standard. The study hence involved a total of 235 colour sheets. The colours were measured using both a conventional colour measuring method and using the multispectral method. Comparison of the results showed the colour difference measurements obtained using the conventional colour measuring method largely agree with those obtained using the multispectral method. The degree of agreement of the values is astonishingly good considering the differences in the principles involved. There was found to be no region of the colour space where the multispectral method gave no usable results. The visual colour matching of these colours was carried out in accordance with DaimlerChrysler specifications by testers at DaimlerChrysler and testers at a paint manufacturer (DuPont Performance Coatings). The matching was carried out using both sample panels and monitor representations based on multispectral images. The two methods of matching showed a high degree of agreement, especially considering the trickiness of visual matching. More detailed evaluation was carried out on the monitor for some of the colours and on the panels for roughly the same number of colours. The two methods were shown to be the same. In the colour space, cases where there is less agreement are prevalent in the red colour region and in the region where some pixels or all pixels of the monitor representation had to be shifted into the region that can be displayed on the monitor using the 'gamut-mapping' procedure. The average degree of agreement was 82 percent. This shows that the monitor matching using the method developed in this work has potential for augmenting or even replacing conventional panel matching. By using the multispectral method as both a colour measuring instrument and a method for visual matching with electronic transfer of the image files, colour communication between paint manufacturers, companies supplying and painting individual parts and the car production plant can be considerably improved and speeded up.


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    Title :

    A new approach to advanced colour management in the automotive industry


    Additional title:

    Fortschritte im Farbmanagement für die Kraftfahrzeugindustrie


    Contributors:


    Publication date :

    2005


    Size :

    13 Seiten, 11 Bilder


    Type of media :

    Conference paper


    Type of material :

    Print


    Language :

    English







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