000K utf8 1100 $c2005 1500 eng 2050 urn:nbn:de:gbv:8-diss-14599 3000 Ekroll, Vebjørn 4000 On the nature of simultaneous colour contrast$hChristian-Albrechts-Universität zu Kiel [Ekroll, Vebjørn] 4030 Kiel$nChristian-Albrechts-Universität zu Kiel 4209 The subject of the present thesis is the phenomenon of simultaneous colour contrast: As is well known, the perceived colour of a given light stimulus depends almost as strongly on the stimulation of neighbouring regions of the visual field as on the local stimulus itself. Thus, the perceived colour of a target stimulus can be manipulated either by changing the colour co-ordinates of the target itself, or, alternatively, by changing the colour co-ordinates of the surround. Classical models of simultaneous contrast are based on the implicit assumption that the changes in perceived colour brought about by these two kinds of manipulation are basically of the same kind, and thus may compensate each other. This ‘compensation assumption’ is equivalent to the widespread assumption that the space of perceived colours is three-dimensional. In principle, though, the well-established facts of trichromatic theory are compatible with a dimensionality of the space of perceived colours higher than three (namely three times the number of differently coloured regions in the visual field). One of the central results of the present investigations is that the compensation assumption seems to be unwarranted in the case of simple centre-surround stimuli. This instilled the expectation that classical methods for measuring simultaneous contrast effects, such as grey settings and asymmetric colour matching, may sometimes be inappropriate, and thus yield misleading results. In further experiments it is shown that this is indeed the case when uniformly coloured surrounds are used. In the case of variegated surrounds, however, matters appear to be much less complicated. This difference seems to be due to impressions of perceptual transparency being evoked by uniform surrounds, but not by variegated ones. 4950 https://nbn-resolving.org/urn:nbn:de:gbv:8-diss-14599$xR$3Volltext$534 4961 https://macau.uni-kiel.de/receive/diss_mods_00001459 5051 150 5550 colour appearance 5550 colour constancy 5550 colour perception 5550 colour scission 5550 colour vision 5550 contrast coding 5550 Farbkontrast 5550 gamut expansion effect 5550 lateral inhibition 5550 perceptual transparency 5550 simultaneous colour contrast 5550 Simultankontrast 5550 Visueller Kontrast