Vision with Isoluminant Colour Contrast: 1. A Projection Technique and Observations

Gregory, Richard L

doi:10.1068/p060113

Cited by 198 publications

(112 citation statements)

References 4 publications

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“…(1) Von der Heydt, Peterhans, and Baumgartner (1984) have recently shown that certain cells in V2 (area 18) of the monkey respond quite strongly to illusory contours, and (2) illusory contours cannot be produced in the absence of luminance contrast between the disks and background texture. For example, if isoluminant color contours (Gregory, 1977), cyclopean targets (Prazdny, 1985), or texture boundaries (Cavanagh, personal communication, 1985) are used to define the cut sectors, then no illusory contours are seen. Also, as noted (a) (b) those in the interstripes are sensitive primarily to bar length ("form").…”

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Capture of stereopsis and apparent motion by illusory contours

Ramachandran

1986

Perception & Psychophysics

132

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The removal of right-angle sectors from four circular black disks created the impression of a white "subjective" square with its four corners occluding the disks ("illusory contours"). The display in one eye was identical to that in the other except that for one eye a horizontal disparity was introduced between the edges of the cut sectors so that an illusory white square floated out in front of the paper. When a "template" ofthis stereogram was superimposed on a vertical squarewave grating (6 cycles/deg) the illusory square pulled the corresponding lines of grating forward even though the grating was at zero disparity. (Capture was not observed if the template was superimposed on horizontal gratings; the grating remained flush with the background). Analogous effects were observed in apparent motion ("motion capture"). Removal of sectors from disks in an appropriately timed sequence generated apparent motion of an illusory square. When a template of this display was superimposed on a grating, the lines appeared to move vividly with the square even though they were physically stationary. It was concluded that segmentation of the visual scene into surfaces and objects can profoundly influence the early visual processing of stereopsis and apparent motion. However, there are interesting differences between stereo capture and motion capture, which probably reflect differences in natural constraints. The implications of these findings for computational models of vision are discussed.361 Figure I shows a square defined by illusory contours (Brady

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confidence: 99%

Capture of stereopsis and apparent motion by illusory contours

Ramachandran

1986

Perception & Psychophysics

132

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“…There is some evidence that illusory contours of the Schumman/Kanisza type are associated with the brightness-domain processing. For example, inducing forms defined solely by hue (i.e., the forms and the surrounding areas are isoluminant) seem to produce, at most, only weak subjective contours (Frisby & Clatworthy, 1975;Gregory, 1977). In the first experiment, we investigated whether illusory contours could be brought about by inducers defined in other domains (spatial and temporal correlation, and flicker) in the absence of monocular luminance-domain cues.…”

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On the nature of inducing forms generating perceptions of illusory contours

Prazdny

1985

Perception & Psychophysics

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“…In this case, we expected that the strength of the · subjective contour would be reduced or that it would not be seen at all. Luminance contrast is known to be critical for the formation of static subjective contours (Frisby and Clatworthy 1975;Gregory 1977), the perception of apparent motion (Ramachandran and Gregory 1978;Cavanagh et al 1985), and the perception of achromatic neon spreading (Bressan 1993 2.2.2 Procedure. Ten stimuli, varying in luminance and chromaticity of the test and surround dots as described above, were presented in random order.…”

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Color from Motion: Separate Contributions of Chromaticity and Luminance

Miyahara

Cicerone

1997

Perception

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Abstract. 'Color from motion' describes the perception of a spread of subjective color over achromatic regions seen as moving. The effect is produced with a stimulus display consisting of colored dots, randomly placed upon a white field, with dots in the test region differing in both chromaticity and luminance from those in the surround. Evidence is presented suggesting that color from motion may be regulated by mechanisms different from those for contour formation and color contrast. (I) Results based on ratings show that, in the absence of luminance differences between the dots in the test and those in the surround regions, chromaticity differences alone are sufficient to produce color spread from motion. As the equiluminance point is approached, subjective color spread is seen despite a reduction in the strength of the subjective contour. Thus, contour formation is not likely to be a prerequisite for color from motion.(2) Color matches show that the hue and saturation of the subjective color spread are determined largely by the chromaticity and the luminance of the dots in the test region, not by those of the dots in the surround for the values explored. This suggests that color from motion may arise in sites distinct from those responsible for the regulation of color contrast.

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Vision with Isoluminant Colour Contrast: 1. A Projection Technique and Observations

Cited by 198 publications

References 4 publications

Capture of stereopsis and apparent motion by illusory contours

Capture of stereopsis and apparent motion by illusory contours

On the nature of inducing forms generating perceptions of illusory contours

Color from Motion: Separate Contributions of Chromaticity and Luminance

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