Illumination-Level Adaptive Color Reproduction Method with Lightness Adaptation and Flare Compensation for Mobile Display

Abstract

Mobile displays such as personal digital assistants and cellular phones encounter various illumination levels, different from the flat panel displays mainly used in indoor environment. In particular, in the daylight condition, the displayed images or text on a mobile display can be darkly perceived, which results in the degradation of sun readability in a mobile display. To overcome this problem, we proposed an illumination level adaptive color reproduction method with a lightness adaptation model and flare compensation. Lightness adaptation is a physiological mechanism to shift the photoreceptor response curve according to the illumination level. Thus, as a mobile phone is carried from an indoor to outdoor environment, the photoreceptor response curve automatically shifts toward a higher luminance to adapt to daylight intensity. Consequently, for a lower intensity emitted from the mobile display, the photoreceptor response curve becomes less sensitive, thereby decreasing the perceived brightness of the displayed image. Moreover, colors produced by mobile display can also be influenced by the flare, defined as ambient light reflected from the display panel, which reduces the maximum chroma of the mobile display gamut. Based on these physiological and physical phenomena, the lightness values of the input image are enhanced by making a linear relation between input luminance value estimated by device characterization and photoreceptor response value calculated from the lightness adaptation model. For the chroma component of the lightness-enhanced input image, chroma compensation is conducted by adding the chroma values of the flare multiplied by the enhancement parameter, depending on the hue plane of the gamut boundary. Throughout the experiment, the proposed algorithm not only reproduces bright and colorful images in the mobile display under daylight conditions, but also produces a solution to improve sunlight readability.

Solving Challenges and Improving the Performance of Automotive Displays

“…In this section, we will cover two perceptual display user experience features that are part of the PDP solution: DRIVEvue, which compensates for shortcomings in visual perception due to a change in ambient lighting conditions, 5‐8 and MYvue, which aims to personalize content rendering based on the driver’s unique visual system and address age‐related visual changes. Just as ambient illumination levels have a large influence on how displayed content is perceived, 5 the aging of the human visual system also plays a role in the degradation of the viewing experience.…”

Color Improvement of Retinex Image Using the Maximum Color Difference Signal Table

“…RGB 색성분의 변화에 따른 휘도(Y)와 색차신호(Cb, Cr), 색상(H) 및 채도(S)는 각각 식(11)과 식(12)와 같이 구 한다 [11] . [1] . 그러므로 제안된 방식과 기존의 방법 들의 처리 결과에 대해 식 (17)과 같이 정의되는 RGB 색 공간에서의 채도를 비교하였다.…”

Improved color reproduction based on CIELAB color space in integrated multi-scale retinex

“…In contrast, the dynamic range acquirable by human eyes is almost 10 5 cd/m 2 . This range too does not cover the entire scene dynamic range, but the human visual system is able, through a mechanism called "lightness adaptation", to simultaneously perceive both light and dark areas of a scene [7] [8]. To obtain similar perception when looking at digital images, tone reproduction methods are used.…”