engleski

Performance of Lightness Calculations in Relation to Chromatic Discrimination

The judgment of lightness of an object is considered and proved as one of the most important tasks of processes of color visualization processed in a three-dimensional space. This makes lightness one of the important parameters for the quality control of colored objects and their color constancy, since changes in the illumination causes lightness inconstancy of a perceived object, especially when it comes to achromatic surfaces. Further, this affect the lightness computation and many experimental results have been already reported which demonstrated deviation of the lightness calculated from the spectral reflectance which influenced development of different computational models for lightness difference calculations. Investigations in this paper were carried out with aim of pointing out the question of reliability of lightness difference calculations testing different color difference formulae on the achromatic part of a colored space. For the purpose of the analysis in this paper three groups of hue samples were chosen: h* 80 &#8211 ; ; ; 100° (yellow), h* 0 &#8211 ; ; ; 10° ; 350 &#8211 ; ; ; 360° (red) and h* 260 &#8211 ; ; ; 280° (blue), considering chroma value C* to be lower than 10. Samples were measured in CIELAB mode spectrophotometrically by means of DataColorŇ type DC SF600 + CT UV. Results were obtained employing DECIELAB/DL*, DECMC(l:c)/DL*, DECIE94/DL* and DECIEDE2000/DL* relationship and were presented in a form of graph. Results of DL* were obtained considering the weighting function values (SL).

Colour; lightness; chroma; computer evaluation; difference evaluation; CMC(l:c); CIE94; CIEDE2000

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