Intermediate-level visual representations and the construction of surface perception.

Abstract Visual processing has often been divided into three stages-early, intermediate, and high level vision, which roughly correspond to the sensation, perception, and cognition of the visual world. In this paper, we present a network-based model of intermediate-level vision that focuses on how surfaces might be represented in visual cortex. We propose a mechanism for representing surfaces through the establishment of "ownership"-a selective binding of contours and regions.

Direction-of-motion discrimination with complex patterns: further observations.

Moving one component of a stimulus comprising two sinusoidal gratings of the same orientation sometimes results in mistaken judgments of the direction of motion. If the component with the higher spatial frequency moves and the stimulus is presented briefly, observers report motion in the direction opposite that which actually occurs. The illusory, or backward, motion appears whether the movement producing it occurs smoothly or as a discrete jump at the midpoint of the stimulus presentation.

Spatial-frequency tuning as a function of temporal frequency and stimulus motion.

Spatial-frequency tuning at two different spatial frequencies was determined by measuring the detectability of a signal grating that was made difficult to see by low- or high-pass visual noise. The signals were vertical sinusoidal gratings of different spatial frequencies. The detectability of the signal was measured in two-alternative forced-choice tasks with different temporal envelopes: (1) a slowly changing raised-cosine (Hanning) window, (2) a rectangularly gated 2-Hz counterphase flickering envelope, and (3) a rectangularly gated 10-Hz counterphase flickering envelope.

Early vision and texture perception.

Texture perception has frequently been studied using textures constructed by repeated placement of micropatterns or texture elements. Theories have been developed to explain the discriminability of such textures in terms of specific features within the micropatterns themselves. For example, Beck observed that a region filled with vertical Ts is readily distinguished from one filled with tilted Ts but not from one filled with vertical Ls.

Dynamically stable 0 degrees phase mode operation of a grating-surface-emitting diode-laser array.

A coherent grating-surface-emitting diode-laser array has demonstrated dynamically stable operation in the 0 degrees phase mode. The array was operated under pulsed conditions, had a peak power output of 44 mW and a large central lobe on axis in the far field, and exhibited single-mode spectral output with better than 18-dB side-mode rejection.

The bleaching of holographic diffraction gratings for maximum efficiency.

The chemical bleaching of absorption holograms produces phase holograms that exhibit higher light efficiency than the holograms from which they were produced. The bleaching of thick absorption type hologram diffraction gratings produced at 6328 A is discussed. The bleached holograms were read out at both 6328 A and 9100 A.