50.3: Proposai of Evaluation Method for Local‐Dimming Backlights

Abstract

A local-dimming control is one of the advanced ways for backlighting an LCD. It balances less power consumption with higher contrast than other ordinary backlighting systems by independently controlling each luminance of backlights according to pictures. On the other hand, a new defect arises; that is, all the backlight units are not completely uniform and luminance of each backlight varies as an input signal changes. We define this defect as "Halo". There have not been presented any particular methods to evaluate "Halo" so far. In this paper, we propose a new method on how to evaluate Halo defect in local-dimming backlight systems with explaining the mechanism why Halo defect arises.

28‐3: Mini‐LED Backlight for HDR Compatible Mobile Displays

“…For the evaluation of Halo, we referred to the evaluation method proposed by Ichioka et al [4]. In this evaluation method, a white window pattern is displayed on a background such as a black one as shown in figure 7, and the distance of the bright part of the Halo extending from the edge of white window to the background is measured.…”

Impact of high-resolution matrix backlight on local-dimming performance and its characterization

“…Halo is a common artifact of local-dimming. In [7] two types of halo were introduced. In this paper, the focus is on the halo on black background.…”

53.1: Invited Paper: Recent Trend of LED Backlight with Local Dimming and its Application for Multi‐Primary‐Color Displays

“…Another example is to add a tonal offset value to all the LED data so that all the LEDs are lit so that they are more luminous than normally calculated. The luminance across the halo will change loosely by using the offset because the luminance from further LED blocks is added to the halo area [5].…”

“…In-plane contrast of a display affects reproducibility of an input image [5]. The in-plane contrast of a display is a combination of in-plane contrast of an LED backlight and contrast of an LCD panel.…”