This paper describes practical algorithms and experimental results concerning illuminant classification. Specifically, we review the sensor correlation algorithm for illuminant classification and we discuss four changes that improve the algorithm’s estimation accuracy and broaden its applicability. First, we space the classification illuminants evenly along the reciprocal scale of color tempera...

The chromaticities of natural daylights cluster around the blackbody locus. We investigated whether the mechanisms that mediate human color constancy embody this statistical regularity of the natural environment, so that constancy is best when the illuminant change is one likely to occur. Observers viewed scenes displayed on a CRT-based stereoscope and adjusted a test patch embedded in the scen...

In this paper we consider the problem of colour constancy; how given an image of a scene under an unknown illuminant can we recover an estimate of that light? Rather than recovering a single estimate of the illuminant as many previous authors have done, in the first instance we recover a measure of the likelihood that each possible illuminant was the scene illuminant. We do this by correlating ...

Human observers can correctly attribute changes in the appearance of a scene either to changes in the incident light or to changes in the spectral-reflectance properties of the scene. This ability was assessed as a function of the time course of illuminant and spectral-reflectance changes. Observers were presented with computer simulations of Mondrian patterns of 49 randomly selected Munsell pa...

Ratios of excitations in each cone-photoreceptor class produced by light reflected from pairs of surfaces in a scene are almost invariant under natural illuminant changes. The stability of these spatially defined ratios may explain the remarkable ability of human observers to efficiently discriminate illuminant changes from changes in surface reflectances. Spatial cone-excitation ratios are not...

Colour is an important and useful feature for object tracking and recognition in computer vision. However, it has the difficulty that the colour of the object changes if the illuminant colour changes. But under known illuminant colour it becomes a robust feature. There are more and more computer vision applications tracking humans, for example in interfaces for human computer interaction or aut...

Rotation of the illuminant source about a subject textured surface can cause catastrophic failure of texture classification schemes. This is due to the variation of texture feature output that can occur when the illuminant direction is varied. This paper uses theory and experiment to show that the outputs of linear texture filters, and their features, are sinusoidal functions of the illuminant’...

The ability of observers to make reliable judgments of surface color despite changes in an illuminant (“color constancy”) has sometimes been attributed to their estimating the spectral properties of the illuminant in order to discount its effects. To test how information about the illuminant contributes to surface-color judgments, observers’ performance in two surface-color-matching experiments...

This paper considers the problem of illuminant estimation: how, given an image of a scene, recorded under an unknown light, we can recover an estimate of that light. Obtaining such an estimate is a central part of solving the colour constancy problem that is of recovering an illuminant independent representation of the re ectances in a scene. Thus the work presented here will have applications ...