The Discriminability of Local Surface Structure

Perception ◽  
1996 ◽  
Vol 25 (4) ◽  
pp. 381-398 ◽  
Author(s):  
J Farley Norman ◽  
James T Todd
Keyword(s):  
Visual System ◽  
Surface Structure ◽  
Human Visual System ◽  
Binocular Disparity ◽  
Qualitative Difference ◽  
Surface Orientation ◽  
Sources Of Information ◽  
Local Surface ◽  
Projected Image ◽  
Image Separation

The ability of observers to discriminate depth and orientation differences between separated local regions on object surfaces was examined. The objects were defined by many optical sources of information simultaneously, including shading, texture, motion, and binocular disparity. Despite the full-cue nature of the displays, the observers' performance was relatively poor, with Weber fractions ranging from 10% to 40%. The Weber fractions were considerably lower for discriminations of surface-orientation differences than for similar discriminations of depth differences. The ability of observers to discriminate surface-orientation differences was approximately invariant over the separation of the regions in the projected image. In contrast, the ability to discriminate depth differences was highly influenced by the amount of image separation. This qualitative difference between the perception of depth intervals and surface-orientation differences suggests that knowledge of depths and orientations may be represented separately within the human visual system.

Interaction between Transparency and Structure from Motion

1992 ◽  
Vol 4 (4) ◽  
pp. 573-589 ◽  
Author(s):  
Daniel Kersten ◽  
Heinrich H. Bülthoff ◽  
Bennett L. Schwartz ◽  
Kenneth J. Kurtz
Keyword(s):  
Visual System ◽  
Structure From Motion ◽  
Human Visual System ◽  
Binocular Disparity ◽  
Rigid Motion ◽  
Motion Information ◽  
Low Level ◽  
Visual Process ◽  
Pictorial Cues

It is well known that the human visual system can reconstruct depth from simple random-dot displays given binocular disparity or motion information. This fact has lent support to the notion that stereo and structure from motion systems rely on low-level primitives derived from image intensities. In contrast, the judgment of surface transparency is often considered to be a higher-level visual process that, in addition to pictorial cues, utilizes stereo and motion information to separate the transparent from the opaque parts. We describe a new illusion and present psychophysical results that question this sequential view by showing that depth from transparency and opacity can override the bias to see rigid motion. The brain's computation of transparency may involve a two-way interaction with the computation of structure from motion.

scholarly journals Perception and misperception of surface opacity

2017 ◽  
Vol 114 (52) ◽  
pp. 13840-13845 ◽  
Author(s):  
Phillip J. Marlow ◽  
Juno Kim ◽  
Barton L. Anderson
Keyword(s):  
Visual System ◽  
Fundamental Problem ◽  
Surface Orientation ◽  
The Body ◽  
Local Surface ◽  
Significant Information ◽  
Scene Structure ◽  
The Relationship ◽  
Opaque Surface ◽  
Insight Into

A fundamental problem in extracting scene structure is distinguishing different physical sources of image structure. Light reflected by an opaque surface covaries with local surface orientation, whereas light transported through the body of a translucent material does not. This suggests the possibility that the visual system may use the covariation of local surface orientation and intensity as a cue to the opacity of surfaces. We tested this hypothesis by manipulating the contrast of luminance gradients and the surface geometries to which they belonged and assessed how these manipulations affected the perception of surface opacity/translucency. We show that (i) identical luminance gradients can appear either translucent or opaque depending on the relationship between luminance and perceived 3D surface orientation, (ii) illusory percepts of translucency can be induced by embedding opaque surfaces in diffuse light fields that eliminate the covariation between surface orientation and intensity, and (iii) illusory percepts of opacity can be generated when transparent materials are embedded in a light field that generates images where surface orientation and intensity covary. Our results provide insight into how the visual system distinguishes opaque surfaces and light-permeable materials and why discrepancies arise between the perception and physics of opacity and translucency. These results suggest that the most significant information used to compute the perceived opacity and translucency of surfaces arise at a level of representation where 3D shape is made explicit.

scholarly journals Processing of first and second order binocular disparity by the human visual system

2012 ◽  
Vol 12 (9) ◽  
pp. 39-39
Author(s):  
C. Quaia ◽  
B. Sheliga ◽  
L. Optican ◽  
B. Cumming
Keyword(s):  
Visual System ◽  
Human Visual System ◽  
Binocular Disparity ◽  
Second Order

Disparity-tuned channels of the human visual system

1993 ◽  
Vol 10 (4) ◽  
pp. 585-596 ◽  
Author(s):  
Lawrence K. Cormack ◽  
Scott B. Stevenson ◽  
Clifton M. Schor
Keyword(s):  
Visual System ◽  
Human Visual System ◽  
Single Unit ◽  
Binocular Disparity ◽  
Random Element ◽  
Stereoscopic Depth ◽  
Detection Thresholds ◽  
Strict Adherence ◽  
Low Level ◽  
Single Unit Recordings

AbstractTraditionally, it has been thought that the processing of binocular disparity for the perception of stereoscopic depth is accomplished via three types of disparity-selective channels – “near,” “far,” and “tuned.” More recent evidence challenges this notion. We have derived disparity-tuning functions psychophysically using a subthreshold summation (i.e. low-level masking) technique. We measured correlation-detection thresholds for dynamic random-element stereograms containing either one or two surfaces in depth. The resulting disparity-tuning functions show an opponent-type profile, indicating the presence of inhibition between disparity-tuned units in the visual system. Moreover, there is clear inhibition between disparities of the same sign, obviating a strict adherence to near-far opponency. These results compare favorably with tuning functions derived psychophysically using an adaptation technique, and with the tuning profiles from published single-unit recordings. Our results suggests a continuum of overlapping disparity-tuned channels, which is consistent with recent physiological evidence as well as models based on other psychophysical data.

Evaluation of the Human Visual System in Cosmetics Foundation Colour Selection

2020 ◽  
Vol 2020 (1) ◽  
pp. 60-64
Author(s):  
Altynay Kadyrova ◽  
Majid Ansari-Asl ◽  
Eva Maria Valero Benito
Keyword(s):  
Visual System ◽  
Human Visual System ◽  
Skin Tone ◽  
Skin Colour ◽  
Psychophysical Experiment ◽  
Spectral Measurements ◽  
Practical Applications ◽  
Subjective Evaluations ◽  
Colour Measurements ◽  
Colour Quantification

Colour is one of the most important appearance attributes in a variety of fields including both science and industry. The focus of this work is on cosmetics field and specifically on the performance of the human visual system on the selection of foundation makeup colour that best matches with the human skin colour. In many cases, colour evaluations tend to be subjective and vary from person to person thereby producing challenging problems to quantify colour for objective evaluations and measurements. Although many researches have been done on colour quantification in last few decades, to the best of our knowledge, this is the first study to evaluate objectively a consumer's visual system in skin colour matching through a psychophysical experiment under different illuminations exploiting spectral measurements. In this paper, the experiment setup is discussed and the results from the experiment are presented. The correlation between observers' skin colour evaluations by using PANTONE Skin Tone Guide samples and spectroradiometer is assessed. Moreover, inter and intra observer variability are considered and commented. The results reveal differences between nine ethnic groups, between two genders, and between the measurements under two illuminants (i.e.D65 and F (fluorescent)). The results further show that skin colour assessment was done better under D65 than under F illuminant. The human visual system was three times worse than instrument in colour matching in terms of colour difference between skin and PANTONE Skin Tone Guide samples. The observers tend to choose lighter, less reddish, and consequently paler colours as the best match to their skin colour. These results have practical applications. They can be used to design, for example, an application for foundation colour selection based on correlation between colour measurements and human visual system based subjective evaluations.

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