The number of discernible colours perceived by dichomats in natural scenes: the influence of different theoretical models

Several models are available to simulate the colour perception of dichromat observers. The goal of this work was to study how much the estimated number of discernible colours in natural scenes depends on the theoretical colour model applied. Twelve images of natural scenes were simulated for trichromats as if they were seen by dichromats. Two theoretical models were used in these simulations. The CIELAB colour volume was estimated to each image for normal observers and dichromats and for each of the models tested. The number of discernible colours was estimated by segmenting the CIELAB colour volume intounitary cubes and by counting the number of non-empty cubes, that is, assuming that all the colours that are inside the same cube could not be discernible. Reductions to less than 10% of the colours perceived by normal trichromats were found to all dichromats regardless the dichromatic colour model used. This result seems to indicate that the estimated chromatic diversity of natural scenes perceived by dichromats is not strongly influenced by the dichromatic colour model used.This work was supported by the Centro de Física of Minho University, Braga, Portugal, by the Fundação para a Ciência e a Tecnologia (grants POSC/EEA-SRI/57554/2004 and POCTI/EAT/55416/2004). João M.M. Linhares was supported by grant SFRH/BD/35874/2007