Inverse display characterization: A two‐step parametric model for digital displays

Abstract— A simple additivity model is often used as a basic model for digital‐display characterization. However, such a simple model cannot satisfy the needs of demanding color‐management applications all the time. On the other hand, systematic sampling of the color space and 3‐D interpolation is an expensive method in terms of measurement and computation time when precision is needed. This paper presents an enhanced method to characterize the XYZ‐to‐RGB transform of a digital display. This parametric method exploits the independence between the luminance variation of the electro‐optic response and the colorimetric responses for certain display types. The model is generally applicable to digital displays, including 3‐DMD projectors, single DMDs, CRTs, LCDs, etc., if the independence condition is satisfied. While the problem to solve is a 3‐D‐to‐3‐D transformation (from XYZ to RGB), the proposed parametric model is the composition of a 2‐D transform followed by a 1‐D transform. The 2‐D transform manages the chromatic aspects and, in succession, the 1‐D transform manages the luminance variations. This parametric digital model is applicable in the field of color management, with the objective of characterizing digital displays and applying a reference look such as a film look.     

Imaging performance of displays: Past,present, and future*

Abstract— Some display devices that were tried unsuccessfully in the past are reviewed briefly. Then the display devices that are in use at present are described and their advantages and disadvantages discussed. Properties where improvements are needed include greater consistency between pictures displayed from the same signals on different devices, greater color gamut, less impairment by ambient illumination, and better resolution. Finally, consideration is given to some of the ways in which these needs may be met.     

Controling color of liquid‐crystal displays

Abstract— Two newly derived characterization models for a liquid‐crystal (LC) display have been tested for five LC‐based displays. Data measured from a series of test colors indicated that all LC‐based displays showed similar characteristics, including an S‐shaped tone curve and poor channel chromaticity constancy. Because they include a hyperbolic function in their definition, the models do not have analytical inverses, and so iterative mathematical techniques are applied. It was shown that a new characterization model based on a hyperbolic function fits the tone curve very accurately with only four coefficients per channel for any type of LCD. In addition, it was also shown that the first derivative of the function provides a means of accurate correction of the chromaticity variation.     

Design of a dual‐f‐number illumination system and its application to DMD™ projection displays

Abstract— A dual‐f/# optical system is evaluated and considered for illumination. Étendue theory has been employed to increase the optical throughput and collection efficiency. A classical Cooke triplet with a dual f/# is included for illustration. As a demonstration of the potential application to projection displays, an elliptically shaped illumination‐pupil system is proposed to increase the optical collection efficiency in the DMD? (Digital Micromirror Device?)‐based projection system. With a dual‐f/# configuration, this design can eliminate the f/2.4 constraint that was caused by the light‐steering action of the narrow ±12° tilt angles on the DMD?. The percentage of increase in the optical collection efficiency is 6.2% in the dual f/2.0 × f/2.4 optical projection system by using ray‐tracing simulation. This method enables a lower than f/2.4 optical design with a high brightness and an adequate contrast ratio in the DMD?‐based projectors.     

A 13‐bit universal column driver for various displays of OLED and LCD

A universal column driver is implemented in a 0.13‐µm high‐voltage CMOS process for not only TFT‐LCD but also OLED applications. The proposed column driver employs 13‐bit linear DAC to cover all gamma curves of display applications and address‐based configuration for intra‐ panel interface protocol to support both TV and IT applications. Measured results demonstrate the average voltage of output channels (AVO) is under 1mv, which satisfies 1‐LSB resolution at 18.5V of AVDD.