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Image Contrast Enhancement Technique for Local Dimming Backlight of Small-sized Mobile Display  

Chung, Jin-Young (Dept. of Electronics Engineering, Kookmin University)
Yun, Ki-Bang (Dept. of Information & Electronic Engineering, Incheon City College)
Kim, Ki-Doo (Dept. of Electronics Engineering, Kookmin University)
Publication Information
전자공학회논문지 IE / v.46, no.4, 2009 , pp. 57-65 More about this Journal
Abstract
This paper presents the image contrast enhancement technique suitable for local dimming backlight of small-sized mobile display while achieving the reduction of the power consumption. In addition to the large-sized TFT-LCD, small-sized one has adopted LED for backlight. Since, conventionally, LED was mounted on the side edge of a display panel, global dimming method has been widely used. However, recently, new advanced method of local dimming by placing the LED to the backside of the display panel and it raised the necessity of sub-blocked processing after partitioning the target image. When the sub-blocked image has low brightness, the supply current of a backlight LED is reduced, which gives both enhancement of contrast ratio and power consumption reduction. In this paper, we propose simple and improved image enhancement algorithm suitable for the small-sized mobile display. After partitioning the input image by equal sized blocks and analyzing the pixel information in each block, we realize the primary contrast enhancement by independently processing the sub-blocks using the information such as histogram, mean, and standard deviation values of luminance(Y) component. And then resulting information is transferred to each backlight control unit for local dimming to realize the secondary contrast enhancement as well as reduction of power consumption.
Keywords
Local Dimming; Backlight LED; Histogram Stretching; Mobile Display; Contrast Enhancement;
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