Russel A. Martin

Color matrix display simulation based on luminance and chromatic contrast sensitivity of early vision

This paper describes the design and operation of a new simulation model for color matrix display development. It models the physical structure, the signal processing, and the visual perception of static displays, to allow optimization of display design parameters through image quality measures. The model is simple, implemented in the Mathematica computer language, and highly modular. Signal processing modules operate on the original image. The hardware modules describe backlights and filters, the pixel shape, and the tiling of the pixels over the display. Small regions of the displayed image can be visualized on a CRT. Visual perception modules assume static foveal images. The image is converted into cone catches and then into luminance, red-green, and blue-yellow images. A Haar transform pyramid separates the three images into spatial frequency and direction-specific channels. The channels are scaled by weights taken from human contrast sensitivity measurements of chromatic and luminance mechanisms at similar frequencies and orientations. Each channel provides a detectability measure. These measures allow the comparison of images displayed on prospective devices and, by that, the optimization of display designs.

The electronic document display : A 6.3-million-pixel AMLCD

This paper describes 6.3-million-pixel active-matrix displays in monochrome and color (1.6 million color groups) with a diagonal dimension of 33 cm (13 in.), first discussed by Martin et al. in 1993. 1 These displays have the largest number of pixels of any AMLCDs thus far reported. The monochrome display is intended for office-automation applications where there is a requirement for electronically controlled image reproduction with characteristics similar to those of a conventional laser print. This display achieves the resolution, luminance, and viewing angle required for these applications through a binary driving scheme.

High-resolution AMLCD for the electronic library system

The Electronic Library System (ELS), is a proposed data resource for the cockpit which can provide the aircrew with a vast array of technical information on their aircraft and flight plan. This information includes, but is not limited to, approach plates, Jeppeson Charts, and aircraft technical manuals. Most of these data are appropriate for digitization at high resolution (300 spi). Xerox Corporation has developed a flat panel active matrix liquid crystal display, AMLCD, that is an excellent match to the ELS, due to its innovative and aggressive design.

Resolution in information display

This paper describes the system tradeoffs related to display type, resolution, and pixel structure, taking examples from the development of binary and grayscale high resolution AMLCDs. Performance is related to the match achieved between the human visual system, the display system and the task assigned. The active matrix liquid crystal display is compared to other technologies at the high acuity levels achieved in a 282 DPI monochrome grayscale and a 141 color groups per inch color grayscale AMLCD. The potential benefits to military aviators of very high resolution displays are outlined as well as the challenges to implement these systems.

Gray-scale/resolution tradeoff

Spatial resolution and grayscale resolution are two image parameters that determine image quality. In this study we investigate the trade-off between spatial resolution and grayscale in terms of the discriminability of steps, measured in bits, away from a standard image. A CRT display was used to simulate black-and-white images with a square-pixel geometry. Natural images and a test pattern consisting of a radially symmetric spatial frequency chirp of increasing radial frequency (called a zone plate) were studied. Multiple versions of each image were produced by varying the simulated pixel size and the number of gray levels and by filtering. Discrimination thresholds for pixel size and number of gray levels were measured for several locations in the parameter space of spatial resolution and grayscale resolution for each image. Unfiltered, low-contrast, Nyquist-filtered, and Gaussian-filtered versions of the images were studied. Resolution levels were always integer divisors of the CRT display resolution, produced by subsampling and pixel-replication. Gray levels were steps that were linear in luminance and that spanned the entire CRT luminance range. Discrimination thresholds were measured using a three-alternative forced-choice one-up-two-down double- random-staircase procedure. Simulation device limitations caused some measurements to be less precise than was desired.