Karel J. G. Hinnen

A New Color Breakup Measure Based on Color Difference Between Fields and Contrast to the Surrounding

Field-sequential-color displays can have low power consumption and high spatial resolution, but can suffer from annoying color breakup. Various approaches to suppress color breakup have been presented in recent literature. However, a suitable color breakup measure is necessary to compare the performances of those approaches, and is also helpful for quick evaluation of algorithms and parameter settings. A perception experiment was carried out to investigate the perceived color breakup with different field color combinations, different light intensities, and different backgrounds. The results indicate that the color difference and the relative contrast between fields have a significant effect on the perceived color breakup, rather than the absolute luminance value, which is different from existing metrics for color breakup visibility. Based on this new insight, a computational metric for color breakup visibility is proposed and discussed, which has a high correlation with the subjective scores (R2 = 0.945).

Local Luminance Boosting of an RGBW LCD

Compared to a conventional RGB LCD, an RGBW LCD is known to result in 50% higher light transmission. However, the reduced aperture for the RGB subpixels lead to reduced luminance for saturated pixels. Consequently, colorful images may appear dull due to a lack of sufficient luminance. In this work it is proposed to address the luminance shortage for bright saturated pixels by boosting a spatially modulated backlight. Whereas best-in-class methods for deriving backlight drive levels either results in high contrast or temporal stability, we propose a reformulation which provide superior contrast and temporal stability. By employing local backlight boosting, the 99.5% percentile of ΔE94 is reduced from 12.3 JND to 4.3 JND on average. Power consumption is reduced by 18% compared to an RGB LCD with local backlight dimming. Additionally, we propose to increase luminance of desaturated pixels in regions of backlight boosting, which results in an average luminance increase of 16% for pixels which are boosted.

46.3: Ultra Wide–Gamut LCD Using a Local Multi–Spectral Backlight

Conventional LCDs cover about 33% of the visible gamut in CIE1976 (u′, v′)-chromaticity space. This paper describes a display concept covering more than 63%. It consists of an LCD and a backlight with 5 LED types. From the spectra, a model is derived. The model is used to examine the gamut. Computations are compared with measurements from a demonstrator.