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Colour constancy is traditionally defined as the invariance of perceived surface colours under changes in the spectral composition of the illuminant. Existing quantitative studies show that, by this definition, human subjects show poor colour constancy. A different and complementary aspect of colour constancy is considered which is concerned with the(More)
Colour constancy is traditionally interpreted as the stable appearance of the colour of a surface despite changes in the spectral composition of the illumination. When colour constancy has been assessed quantitatively, however, by observers making matches between surfaces illuminated by different sources, its completeness has been found to be poor. An(More)
A set of 42 photographs of real-world scenes were filtered by convolution with a Laphacian-of-Gaussian kernel. The linear density of zero-crossings along notional lines in the filtered images was measured as a function of the orientation of those lines. The zero-crossing density was found to be greatest along near-vertical lines and least along horizontal(More)
Four issues concerning colour constancy and relational colour constancy are briefly considered: (1) the equivalence of colour constancy and relational colour constancy; (2) the dependence of relational colour constancy on ratios of cone excitations due to light from different reflecting surfaces, and the association of such ratios with von Kries'(More)
Arrays with horizontal or vertical texture boundaries formed by element orientation and length cues were displayed, and the texture boundary formed by one cue was specified as the target. The boundaries formed by the two cues were coincident on some trials and orthogonal on others. Observers' accuracy in reporting the orientation of the target boundary was(More)
The extent and persistence of practice effects on serial performance in the Farnsworth-Munsell 100-Hue test (100-Hue test) were evaluated in an experiment in which six subjects performed the 100-Hue test up to 17 times over six weeks, and then once more after 7 months. A practice effect occurred which was highly statistically significant for the group as a(More)
The human eye is unique amongst those of primates in having white sclera against which the dark iris is clearly visible. This high-contrast structure makes the gaze direction of a human potentially easily perceptible to others. For a social creature such as a human, the ability to perceive the direction of another's gaze may be very useful, since gaze(More)
There is a class of multiple-alternative forced-choice psychophysical procedures in which the subject is required to identify which one of a number of stimuli differs from the remaining stimuli, without having to consider the direction or sign of the difference. A table giving values of the discrimination index d' as a function of the proportion of correct(More)
  • B. J Craven
  • Investigative ophthalmology & visual science
  • 1993
PURPOSE To investigate and describe a hitherto unreported scoring artifact in the Farnsworth-Munsell 100-hue Test, arising from the grouping of the caps into four boxes, which causes caps near the ends of a box to score less than caps near the center of a box. This artifact is in addition to a previously reported one, which causes caps near the end of a box(More)
Professional development for academic staff in Higher Education is always more interesting and inspiring if good practice can be embedded in a way which is meaningful and relevant to the individual. The current project focuses on raising awareness of significant or difficult parts of a course, and promoting the exchange of good practice using a wiki(More)