In this study the purpose was to develop a computational surface model, which gives an equal computed chromaticity difference for equal perceived chromaticity difference in every part of the color space. The computational surface model assess chromaticity differences based on the surfaces defined by an ellipse data set and the two chromaticity points whose chromaticity difference is to be calculated. The distances along the surfaces are calculated by a method based on the Weighted Distance Transform On Curved Space (WDTOCS). The ellipse data sets are the MacAdam ellipses in the CIE 1931 (x,y)-chromaticity diagram and the ellipses which are fitted from the visual color difference measurements used in deriving the CIE DE2000 color difference formula in the CIELAB color space. In general the ellipse data set can be any set of planar chromaticity ellipses. The chromaticity differences calculated along the surfaces correct the planar chromaticity values, thus these differences match better with perceived chromaticity differences. The experiments are made in the vicinity of the chromaticity difference ellipses and the results are contrasted with CIE DE2000.