The Perceptual Basis of Some Rules of Thumb in Photography

Lecture
Datum: 
05. April 2011
Beginn: 
17:15
Ende: 
18:45
Raum: 
W0-135

Abstract

We communicate increasingly with visual imagery such as realistic pictures (e.g., photographs, computer graphic images, perspective drawings and paintings). People are readily able to interpret pictures, but the means by which they do so is poorly understood.

Photographers utilize many guidelines for creating natural-looking pictures. One guideline concerns the lens focal length required to produce pictures that are not spatially distorted. Photography texts recommend choosing a focal length of 50mm. There are two phenomena related to this guideline. One is perceived spatial distortions in wide-angle (short focal length) pictures. I will argue that the perceived distortions are caused by the perceptual mechanisms people employ to take into account oblique viewing positions. The second phenomenon is perceived depth in pictures taken with different focal lengths. The textbooks argue that pictures taken with short focal lengths expand perceived depth and those taken with long focal lengths compress it. I will argue that these effects are due to a combination of the viewing geometry and the way people typically look at pictures.

Another guideline concerns the camera aperture and depth-of-field blur. Photography textbooks do not describe a quantitative rule and treat the magnitude of depth-of-field blur as arbitrary. I examine apertures, lenses, and image formation. From that examination, I argue that there is a natural relationship between depth-of-field blur and the 3D layout of the photographed scene. Human viewers are sensitive to this relationship. In particular, depicted scenes are perceived differently depending on the relationship between blur and 3D layout.

Understanding the perceptual basis of these guidelines provides insight into how to construct photographs, perspective paintings, and computer graphic images for more effective visual communication.

Research Interests

Visual space perception, 3d vision, multi-sensory integration, virtual reality, visually guided navigation

Research Summary

We use our sensory systems for environmental information: to guide our actions with respect to goals and obstacles, to categorize and recognize objects, and much more. We are interested in the visual system's capacity to determine the 3d layout of the environment. This is an interesting computational problem because the 3rd dimension has to be inferred from the 2d retinal images. We conduct rigorous behavioral experiments coupled with quantitative modeling to investigate this process. We are also very interested in developing displays that allow the use of 3d cues for medical imaging, operation of remote vehicles, and more. Another important area of research in our lab is the use of other sensory signals, such as touch, hearing, and the vestibular system, to augment 3d perception and object recognition. We are particularly interested in how those signals are combined with visual signals to form coherent percepts.

Academic Background

  • Occidental College (1966-1970), B.A. in Psychology.
  • University of California, San Diego (1971-1973), M.A. in Experimental Psychology.
  • Univ. of Minnesota (1973-1976), Ph.D. in Developmental Psychology.
  • University of Texas at Austin (1976-1982), Assistant Professor of Psychology; (1982-1984), Associate Professor.
  • University of California at Berkeley (1984-1989), Associate Professor of Optometry; (1989- present), Professor of Optometry; (1985-present), Adjunct Professor of Psychology.
  • University of California at Berkeley, Chairman of the Vision Science Program (1995-2002).

Selected Publications

  • C.S. Royden, M.S. Banks, J.A. Crowell. The perception of heading during eye movements. Nature, 1992.
  • B.T. Backus, M.S. Banks, R. van Ee, J.A. Crowell. Horizontal and vertical disparity, eye position, and stereoscopic slant perception. Vision Research, 1999.
  • M.O. Ernst, M.S. Banks. Humans integrate visual and haptic information in a statistically optimal way. Nature, 2002.
  • J.M. Hillis, M.O. Ernst, M.S. Banks, M.S. Landy. Combining sensory information: Mandatory fusion within, but not between, senses. Science, 2002.
  • M.S. Banks, S. Gepshtein, M.S. Landy. Why is spatial stereoresolution so low? Journal of Neuroscience, 2004.
  • D. Vishwanath, A.R., Girshick, M.S. Banks. Why pictures look good when viewed from the wrong place. Nature Neuroscience, 2005.