This is the personal webpage of Jeroen Granzier
webpage of Jeroen Granzier
Personal webpage of Jeroen Granzier » Perceiving the illumination

Perceiving the illumination

Looking at our own phenomenological experience we have a feeling that we are capable of perceiving changes in daylight. For example, at sunset, we sense a reddish glow to things. By looking at the same outdoor scenes at various times of the day, through seasonal changes and under overcast or sunny skies, one realizes that the same object can appear to be of a different color under different natural illuminants. These object’s color changes under changes in natural daylight can, however, be very sophisticated to the untrained eye.

My research deals with the question whether an observer can represent, simultaneously, the color of a surface and that of the light illuminating it. There is to date little experimental evidence for such multidimensional perceptual responses for chromatic scenes. 

My research (in collaboartion with Eli Brenner & Jeroen Smeets) showed that we are poor in perceiving the color of the illumination. Moreover, we showed that the presence of familar objects does not help in perceiving the illuminants' color.

Recent results (in collaboartion with Matteo Valsecchi; see: http://www.allpsych.uni-giessen.de/matteo/) showed that observers are also quite poor in using changes in chromaticty and brightness of daylight in estimating the more ecological valid questions of estimating season, time of day and outside temperature.

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Can you determine whether this picture was taken at sunrise or sunset?

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An experiment in which we tested whether the presence of the familar objects (fruits and vegetables) are helpful in estimating the illuminants' chromaticity.

Another example of a scene containing either familiar obejcts (figure A) and when a scene does not contain familiar objects (Figure B). Familiar objects do not appear to be helpful in estimating the illumination.  

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