Abstract

An adaptive one-dimensional (1-D) dimming technique for liquid crystal displays that compensates for nonuniform backlight distribution is proposed. Dimming techniques that do not consider luminance distribution may cause severe visual artifacts, such as a block artifact. However, an adaptive 1-D dimming technique that considers luminance distribution can reduce power consumption without causing any visual artifacts. Hardware implementation results verified that our method achieved lower power consumption compared to nondimming techniques and removed block artifacts from International Electrotechnical Commission 62087 standard images. The power consumption using the proposed method ranged from 85.5% to 94.7% compared to nondimming techniques. Furthermore, the contrast ratio increased by up to 231% and 165% on average compared to non- dimming techniques. © The Authors. Published by SPIE under a Creative Commons Attribution 3.0 Unported License. Distribution or repro- duction of this work in whole or in part requires full attribution of the original publication, including its DOI. (DOI: 10.1117/1.OE.54.7.073111)

Highlights

  • If pixels are compensated based on Eq (6), severe block artifacts may be caused because BLUi does not fully reflect the luminance distribution over the screen

  • Equations (3) and (4) are considerably complex to be implemented on the field-programmable gate array (FPGA) board, we made eight look-up tables (LUT) corresponding to the light-emitting diode (LED) units

  • We implemented 0-D dimming in which LEDs were placed at the lower edge of the liquid crystal displays (LCDs) panel and divided into eight units; we assumed 1-D dimming techniques for comparison

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Summary

Introduction

The increased power consumption of liquid crystal displays (LCDs) has become a concern.[1,2,3,4,5,6] To reduce power consumption while increasing image quality in LCDs, various technologies have been studied such as backlight dimming,[7,8,9,10,11,12,13,14,15] inversion methods,[16,17,18] and charge sharing methods.[19,20,21,22,23,24] Based on a demand for slim designs and low power consumption, a side-lit light-emitting diode (LED) backlight unit (BLU) has been widely adopted in mobile LCD applications and in large LCDs.[9,10,11,12,13,14]. We propose an adaptive 1-D dimming technique for reducing the power consumption and increasing the image quality of LCDs. Through the analysis of input image data and BLU luminance distribution, our proposed 1-D dimming technique selectively dims LEDs only when the compensated image guarantees a net power benefit and higher image quality. Conventional methods compensate for the dimmed luminance by increasing image data as in Eq (6) without considering the nonuniform luminance distribution of the BLU.[7] If pixels are compensated based on Eq (6), severe block artifacts may be caused because BLUi does not fully reflect the luminance distribution over the screen. We suggest a novel pixel compensation as follows: Yxy 1∕γ BLUFull (7)

Experimental Results
Power Consumption Reduction
Contrast Enhancement
Block Artifact Elimination
Conclusion

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