a novel dithering algorithm for high color depth … · a novel dithering algorithm for high color...

A Novel Dithering Algorithm A Novel Dithering Algorithm for High Color Depth and for High Color Depth and

High Color Performance: HiHigh Color Performance: Hi--FRCFRC

Seung-Woo Lee, Sang-Soo KimAdvanced R & D Group, R & D Center, LCD

Business, Samsung Electronics Co.SID 2004

FAE Sec. 4 Vincent

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Abstract

� Conventional FRC can display only 16,194,277 colors with 6-bit source D-IC’s.� “Hi-FRC” enables full (16,777,216) color on an LCD

panel.

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Dimming FunctionDimming Function

� Dimming� The CCFL brightness is varied by varying the output current,

etc. using an external or other signal. Dimming methods include pulse width modulation (PWM), voltage and current dimming.

� PWM(Pulse Width Modulation)� This method uses a pulse signal to dim the lamp. The dimming

range can be varied between 10 and 100%.

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FRC and DitheringFRC and Dithering

� FRC is achieved by controlling on and off pixels over multiple frames. (Temporal)

� Static dithering regulates the number of on and off pixels in a small defined pixel group. (Spatial)

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FRC Driving MethodFRC Driving Method

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Dithering Driving MethodDithering Driving Method

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6bit => 8bit0 => 00.25 => 10.5 => 20.75 => 31 => 42 => 83 => 12. . . .. .

63 => 252253254 255

t

L

0

1 ( ) 75.0011141

=+++=L

Number of color of 6bit+FRC=(256-3)3=(253)3=16,194,277

The human eyes average the luminance and feelthe brightness is the same as grayscale “0.75”

frame time

FRC

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Temporal Temporal AAverage of FRC verage of FRC AAlgorithmlgorithm

127 (01111111)2 = > 31,32,32,32

126 (01111110)2 = > 32,31,32,31

011111

100000

100000

100000

100000

011111

100000

011111

8 bits input => 6 bits output

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Spatial Average of FRC Spatial Average of FRC AlgorithmAlgorithm

127 (01111111)2 = > 31,32,32,32

011111

100000

100000

100000

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Spatial Dithering and Spatial Dithering and Temporal Averaging PatternTemporal Averaging Pattern

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Conventional FRC is Limited to Conventional FRC is Limited to only 253 Luminance Levelsonly 253 Luminance Levels

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HiHi--FRC Enables a Higher Number FRC Enables a Higher Number of Available Colorsof Available Colors

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An Example of HiAn Example of Hi--FRC for FRC for Higher Color DepthHigher Color Depth

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Temporal Averaging Temporal Averaging Concept of HiConcept of Hi--FRCFRC

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Spatial Dithering Concept Spatial Dithering Concept of Hiof Hi--FRC (011)FRC (011)

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The Measured LuminanceThe Measured Luminance