Effects of viewing distance and visual angle on metameric matches.
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Color Perception↗
Biomedical subjects
F Pratt
Publications and source records attributed to F Pratt.
Effect of distance on heterochromatic matching.
The brightness of colors in a number of paintings by Francis Pratt appeared to vary as a function of the viewing distance. These pictures were composed of narrow strips of different colors varying in brightness and saturation. Five experiments were undertaken to replicate and study this effect under controlled conditions using heterochromatic brightness matching of various pairs of colored stimuli. The subjects were first-year students in psychology, participating as a course requirement. The number of subjects varied in the different experiments, between 6 and 9. The relative brightness of blue as compared to red, orange, and yellow-green varied as a function of viewing distance. The relative brightness of the blue decreased as distance increased. By varying the physical size of the stimuli it was possible to keep the angle subtended at the retina constant for two distances and the effect remained. Any explanation must therefore account for the finding that the effect is not due to the apparent size of th stimuli.
Color Perception↗
The contribution of colour to three-dimensional ambiguities in paintings and drawings.
This paper is about kinds of visual ambiguity that concern the author as a painter. Some effects of incompatible depth cues on the experience of looking at paintings and drawings are discussed. Particular attention is given to the role of colour as a depth cue. It is suggested that areas of identical pigmentation on different parts of a picture surface tend to be interpreted as being on the same plane. Where this interpretation is incompatible with other depth cues 'visual tension' results, the degree of tension being dependent on the relative strength of the cues involved. This hypothesis is illustrated and elaborated with the help of a number of line drawings.
Art↗