Optical component differentiation (diffusers and light processing elements) between reflective displays based on
Interferometric Modulation (IMOD) and typical transmissive (LCD) displays is discussed. We characterize optimized
diffusers for a front light of reflective displays and present the key differentiation data with important metrology tools to
monitor the image quality. Drawing on our experience, we outline guidance going forward.
The leakage characteristics of the buried photodiode structure have been investigated in direct color CMOS image
sensor with a stacked photodiode (PD) structure tailored for detecting red, green and blue light. Image quality was
investigated showing that the blue photodiode has surface related effects while the red and green PDs do not. From
these experiments, it is found that the activation energy of PDs display dependence on area, periphery, and corners and
the corner component dominants. Leakage characteristic of PDs show similar behavior to normal n+pwell diode of
similar structure. Also the separate contribution from the area, periphery and corners, and their relationship to STI was
analyzed by TCAD.
For the first time, we have analyzed the vertical buried photodiode structure and found that corner components on red
and green PD can be source of leakage current. We also found that surface contact of blue PD can be a noise source,
reducing image quality. Therefore, to maintain high image quality, the blue photo diode of a CIS has to be designed as
a buried structure and the connections to the buried red and green PDs has to be free from STI sidewall contact.
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.
KEYWORDS: Spatial resolution, Visual process modeling, CRTs, Image quality, Image resolution, Visualization, Human vision and color perception, Visibility, Instrument modeling, Linear filtering
In a series of papers presented in 1994 at SPIE1' SID2 and IDRC3, we examined the grayscale/resolution trade-off for natural images displayed on devices with discrete pixellation, such as AMLCDs. In the present paper we extend this study by examining the grayscale/resolution trade-off for text images on discrete-pixel displays. Haiftoning in printing is an example of the grayscale/resolution trade-off. In printing, spatial resolution is sacrificed to produce grayscale. Another example of this trade-off is the inherent low-pass spatial filter of a CRT, caused by the point-spread function of the electron beam in the phosphor layer. On a CRT, sharp image edges are blurred by this inherent low-pass filtering, and the block noise created by spatial quantization is greatly reduced. A third example of this trade-off is text anti-aliasing, where grayscale is used to improve letter shape, size and location when rendered at a low spatial resolution. There are additional implications for display system design from the grayscale/resolution trade-off. For example, reduced grayscale can reduce system costs by requiring less complexity in the framestore, allowing the use of lower cost drivers, potentially increasing data transfer rates in the image subsystem, and simplifying the manufacturing processes that are used to construct the active matrix for AMLCD (active-matrix liquid-crystal display) or AMTFEL (active-matrix thin-film electroluminescent) devices. Therefore, the study of these trade-offs is important for display designers and manufacturing and systems engineers who wish to create the highest performance, lowest cost device possible. Our strategy for investigating this trade-off is to generate a set of simple test images, manipulate grayscale and resolution, predict discrimination performance using the ViDEOSSarnoff Human Vision Model (see Larimer et al., 1994), conduct an empirical study of thscrimination using psychophysical procedures, and verify the computational results using the psychophysical results.
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.
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.
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.
Access to the requested content is limited to institutions that have purchased or subscribe to SPIE eBooks.
You are receiving this notice because your organization may not have SPIE eBooks access.*
*Shibboleth/Open Athens users─please
sign in
to access your institution's subscriptions.
To obtain this item, you may purchase the complete book in print or electronic format on
SPIE.org.
INSTITUTIONAL Select your institution to access the SPIE Digital Library.
PERSONAL Sign in with your SPIE account to access your personal subscriptions or to use specific features such as save to my library, sign up for alerts, save searches, etc.