Backlight Unit Excessive Dimming Based on Perceptual Image Analysis

Seungwoo Yang,Hyungsik Shin,Jaehee You

doi:10.3390/app11031039

Abstract

A method to maximize backlight dimming of liquid crystal displays (LCDs) based on human visual system are proposed to minimize power consumption of display panels. Based on images, the proposed method optimizes global, local, and red, green, blue (RGB) backlight dimming by enhancing dimming about 12% on average for various images while maintaining tolerable degradation of perceived image qualities in pixel saturation areas. The method considers and utilizes the brightness sensitivity and contrast response functions of human visual system using the mean luminance and the contrast of an image, which are mathematically modelled to allow optimization for display panels and application areas. A simulator that can calculate various dimming cases with the evaluations of numerical and perceptual image qualities as well as power consumption amount is introduced. With pattern and real photo images, the degree of power savings and the preservation of image quality of the proposed method are verified to outperform conventional approaches with high scores of the mean opinion score (MOS) and the structural similarity index measure (SSIM) over 0.97 while saving more than 10% of power dissipation.

Highlights

BacklightDimming DimmingBased Basedon onImage ImageAnalysis AnalysisBacklightdimming dimmingminimizes minimizesthe thebacklight backlightbrightness brightnessand andcompensates compensatesimage imagequalqualBacklight ityloss lossby bycorrecting correcting brightness of the image through compensation, ity thethe brightness of the image through pixelpixel compensation, whichwhich proproportionally increases the pixel value, that is, the transmittance of the panel.Together portionally increases the pixel value, that is, the transmittance of the panel
To make Saturated Pixel Brightness Sensitivity Slope (SPBSS) vary, which depends on brightness, the same excessive dimming was applied to the two images, and the results are shown in Figure 6b,d, respectively
Excessive dimming is possible for the following cases with less power consumption

Summary

Introduction

Background BacklightDimming DimmingBased Basedon onImage ImageAnalysis AnalysisBacklightdimming dimmingminimizes minimizesthe thebacklight backlightbrightness brightnessand andcompensates compensatesimage imagequalqualBacklight ityloss lossby bycorrecting correcting brightness of the image through compensation, ity thethe brightness of the image through pixelpixel compensation, whichwhich proproportionally increases the pixel value, that is, the transmittance of the panel.Together portionally increases the pixel value, that is, the transmittance of the panel. Background BacklightDimming DimmingBased Basedon onImage ImageAnalysis Analysis. Backlightdimming dimmingminimizes minimizesthe thebacklight backlightbrightness brightnessand andcompensates compensatesimage imagequalqualBacklight ityloss lossby bycorrecting correcting brightness of the image through compensation, ity thethe brightness of the image through pixelpixel compensation, whichwhich proproportionally increases the pixel value, that is, the transmittance of the panel. Together portionally increases the pixel value, that is, the transmittance of the panel. Together with with the maximum pixeldimming value dimming Pixel dimming), shows thepixel outthe maximum pixel value Figure 1Figure shows 1the output put pixelfunction mappingoffunction the input before and after excessive dimming. The mapping the inputofpixel beforepixel and after excessive dimming

Methods

Results

Conclusion