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Showing papers on "Contrast (vision) published in 1971"


Journal ArticleDOI
TL;DR: Inspection of a high‐contrast adapting grating produces two visual after‐effects: (a) the contrast threshold is raised for test gratings of similar spatial frequency to that of the adapting pattern and (b) the apparent spatial frequency of test grating shifts away from that ofThe adaptinggrating.
Abstract: 1. Inspection of a high-contrast adapting grating produces two visual after-effects: (a) the contrast threshold is raised for test gratings of similar spatial frequency to that of the adapting pattern and (b) the apparent spatial frequency of test gratings shifts away from that of the adapting grating—higher frequencies seem higher and lower ones lower than they really are. 2. Both after-effects are orientation-specific. A horizontal adapting grating influences neither the threshold nor the apparent spatial frequency of vertical test gratings. 3. The magnitude of the two after-effects was measured with vertical test gratings as a function of (a) tilt of a high-contrast adapting grating and (b) contrast of a vertical adapting grating. 4. At all frequencies of the test grating, the decline of both after-effects produced by an increase in tilt of approximately 6¾° could be matched by a reduction in contrast by a factor of 2. 5. We take this as evidence for a common neural origin for these two visual phenomena.

270 citations



Journal ArticleDOI
19 Feb 1971-Science
TL;DR: The lateral inhibitory mechanisms found in the retina and geniculate can account for luminance border enhancement, but not entirely for simultaneous brightness or color contrast, for which other cortical processes of some sort must be responsible.
Abstract: The responses of single units in the monkey lateral geniculate nucleus to different portions of figures which differed from their backgrounds in color and brightness were examined. Border enhancement was found in the response to luminance figures but not in the response to color figures. In addition, cells showed border enhancement only in the case of a figure which produced an increment (as opposed to a decrement) in their firing rates. In situations in which very striking brightness contrast is seen perceptually, the cells do not show the corresponding changes in firing rate across the whole pattern. The lateral inhibitory mechanisms found in the retina and geniculate can thus account for luminance border enhancement, but not entirely for simultaneous brightness or color contrast, for which other cortical processes of some sort must be responsible.

94 citations


Journal ArticleDOI
TL;DR: The task consisted of determining the size of the retinal area within which photic stimulation of the periphery induces apparent brightness changes of the central portions of the centre.
Abstract: Foveal perceptive fields (center plus surround) for human vision were investigated by means of contrast illusions in grids and bars. The task consisted of determining the size of the retinal area within which photic stimulation of the periphery induces apparent brightness changes of the central portions. The mean of the individual thresholds obtained in four experiments suggests a total field diameter of 17.8 min of arc (with an estimated 4.0′ corresponding to the center) for on-and off-center fields. It is assumed that this average value refers to perceptive fields of retinal ganglion cells. The significance of eye movements and afterimages in contrast vision and their possible influence on these measurements is discussed.

63 citations


Journal ArticleDOI
TL;DR: The detectability of sinusoidal gratings comprised of either one or many cycles was measured in veiling luminances the spatial frequencies of which were either narrow‐ or broad‐band.
Abstract: 1. The detectability of sinusoidal gratings comprised of either one or many cycles was measured in veiling luminances the spatial frequencies of which were either narrow- or broad-band. 2. In narrow-band noise, the single-cycle grating was detected with approximately 0·6 log units less contrast than the many-cycle grating. On the other hand when both broad-band and narrow-band noise were present, there was no measurable difference in the detectability of the two types of grating. 3. The results are interpreted as supporting the hypothesis of Campbell & Robson (1968) that spatially varying luminance patterns are processed by mechanisms selectively sensitive to limited ranges of spatial frequencies.

58 citations


Journal ArticleDOI
TL;DR: Binocular depth perception arising from stereoscopic presentation of two gratings of different spatial frequencies is investigated and a model is proposed for a mechanism of stereoscopic depth perception based on the comparison of spatial frequency content in the two retinal images.

46 citations


Journal ArticleDOI
17 Nov 1971-Nature
TL;DR: The ability to distinguish between a striped target or a grating and a non-striped target, when the average intensity is held constant, depends on the relative intensity (contrast) and size of the light and dark stripes.
Abstract: THE ability to distinguish between a striped target or a grating and a non-striped target, when the average intensity is held constant, depends on the relative intensity (contrast) and size of the light and dark stripes. Contrast and stripe size, however, are not independent in that the minimum (threshold) contrast necessary to detect a grating varies with the spatial frequency (cycles/degree of visual angle) of the grating. The function relating contrast sensitivity, the reciprocal of threshold contrast, to spatial frequency is the contrast sensitivity function. When expressed this way, peak contrast sensitivity is found at moderate spatial frequencies, with sensitivity declining slowly at lower spatial frequencies and rapidly at higher spatial frequencies1. At maximum contrast, the highest spatial frequency (finest grating) that is seen as a grating is a measure of the spatial resolution of the visual system and can be considered a measure of visual acuity2.

29 citations




Book ChapterDOI
01 Jan 1971
TL;DR: The difference thresholds for luminance discrimination are nearly as low in cats as in men, and the same is true of the thresholds for simultaneous contrast.
Abstract: Cats are able to discriminate between simple patterns such as dots, circles, bars, triangles etc. Even if the optic nerves are destroyed up to 98% on both sides, cats can be trained to discriminate, for example, the symbol 9 from the symbol 6 with the remaining 2% of optic nerve fibers (Norton, Galambos and Frommer, 1967). The difference thresholds for luminance discrimination are nearly as low in cats as in men, and the same is true of the thresholds for simultaneous contrast (Snigula and Grusser, 1968). The simultaneous contrast enhancement of light dark borders is one of the essential initial operations for pattern discrimination in the visual system.

11 citations


Journal ArticleDOI
TL;DR: Two experiments demonstrate that temporal resolution is a function of visual adaptation, and it is suggested that the mechanism ofVisual adaptation is sufficient to account for the relation between intensity and latency.


Book ChapterDOI
01 Jan 1971


Journal ArticleDOI
TL;DR: This reexamination supports the original conclusion that whiteness contrast and separation in stereoscopic depth are related directly and not through the presence of any uncontrolled artifacts.
Abstract: MERSHON, D. H. Evidence for the relationship of depth adjacency to contrast. A response to Lie. Scand. J. Psychol., 1971, 12, 295–302.–Some recent studies indicated that separation of test and induction objects from each other in stereoscopic depth will produce a decrease in simultaneous whiteness contrast. Lie has suggested, however, that this change was merely the result of experimental artifacts such as accommodative blurring, double images, and the presence of the small lateral displacements used to produce the stereopsis. Each of these possible artifacts has been considered, and the original experiments (as well as those of Lie) have been reexamined, in light of these considerations. This reexamination supports the original conclusion that whiteness contrast and separation in stereoscopic depth are related directly and not through the presence of any uncontrolled artifacts.





Journal ArticleDOI
M. Lang1
TL;DR: In this paper, a space-dependent contrast function is introduced to discuss the interference pattern of transmittance holograms, and spots with contrast equal to unity can be achieved in single exposure as well as in multiple exposure techniques.



Book ChapterDOI
01 Jan 1971
TL;DR: This method is term the direct visual measurement of luminance, in contrast with the indirect methods in which luminance is measured with the aid of another quantity.
Abstract: Since luminance, among the photometric quantities, is the only one that can be perceived as such by the eye, only luminance can be measured directly by comparison with another luminance. We shall term this method the direct visual measurement of luminance, in contrast with the indirect methods in which luminance is measured with the aid of another quantity.


Journal ArticleDOI
TL;DR: In this paper, the authors present a technique which they have found to be useful for rating the contrast characteristics of color tubes under monochrome mode of operation, and no discussion will be made of contrast due to color differences between areas in a color image.
Abstract: Contrast (numerically) is what you make it ! By this, we mean that there are many variables involved in producing the final image on a color receiver. Some of these are controllable and some are not. The "number" used to express contrast can vary over wide limits, depending on the measurement techniques involved in determining the number itself. This is why the method used in obtaining a given set of contrast data must be spelled out carefully if the data are to be fully understood. We are presenting, here, a technique which we have found to be useful for rating the contrast characteristics of color tubes under monochrome mode of operation. No discussion will be made of contrast due to color differences between areas in a color image. This is a field by itself and well beyond the scope of this paper.

Journal ArticleDOI
TL;DR: The authors investigated the difference in temperature perception between two experiments and found that perceptual assimilation does not occur; instead, large temperature shifts result in periods of tingling or numbness which appear to mask thermal sensations.
Abstract: Contrast in temperature perception was investigated in two experiments to follow up a previous report of perceptual assimilation. The results suggest that perceptual assimilation does not occur; instead, large temperature shifts result in periods of tingling or numbness which appear to mask thermal sensations.

Journal ArticleDOI
01 Jan 1971-Strain
TL;DR: In this paper, a technique for the preparation of contact-copy prints of gratings by means of reflex photography is described, which gives increased contrast and definition compared with classical methods of preparing prints.
Abstract: A technique is described for the preparation of contact-copy prints of gratings by means of reflex photography. The authors suggest that the method gives increased contrast and definition compared with classical methods of preparing prints.