Variable-Resolution Imagery for Flight Simulation

摘要

A position-varying, low-pass filter was used to produce variable-resolutionimages whose spatial frequency content varies as a function of distance from their center. Such images can be matched in some sense to the spatial inhomogeneities of the human visual system, and thus may be visually acceptable even though they contain less information than an unprocessed version of the same image. Following a discussion of image representation with nonuniform sampling and of the concept of locally bandlimited spaces, two experiments were performed to visually assess variable-resolution images. In Experiment 1, images were generated using a series of distortion functions (differing in central blur, peripheral blur, and blur gradient) chosen to approximate cortical magnification functions (CMFNs) derived from existing anatomical and psychophysical data. The distortion functions, corresponding to the images that were just discriminable from an unprocessed image, were used to define the wide-field CMFN associated with changes in blur discrimination across the visual field. In Experiment 2, blur thresholds were measured using apertures in the form of either circles or 3 deg-wide angular segments centered in either 15 deg or 30 deg eccentricity. Differences in blur discrimination for the two stimulus configurations, matched in area, suggest that the spatial organization of the visual mechanisms underlying blur discrimination changes with eccentricity. Finally, the perceptual data obtained here were used to efficiently sample and represent a variable-resolution image. Cortical magnification factor, Imagery, Visual receptive fields, Flight simulation, Nonuniform sampling, Flight simulation imagery, Variable resolution.