Video display apparatus

• US 20080186413A1
• Filed: 12/20/2007
• Published: 08/07/2008
• Est. Priority Date: 02/02/2007
• Status: Active Grant

• Current Assignee: Mitsubishi Electric Corporation
• Original Assignee: Mitsubishi Electric Corporation
• Inventors: Sugiura, Hiroaki, Someya, Jun, Yasui, Hironobu, Tsutsumi, Kazuhiko, Kyuma, Kazuo
• Granted Patent: US 8,139,157 B2
• Time in Patent Office: Days
• US Class Current: 348/739
• CPC Class Codes: H04N 5/147 Scene change detection
• CPC Class Codes: H04N 5/20 Circuitry for controlling amplitude response
• CPC Class Codes: H04N 9/68 for controlling the amplitude of colour signals, e.g. automatic chroma control circuits H04N9/71, H04N9/73 take precedence; camera processing pipelines for controlling the colour saturation of colour signals H04N23/86

Abstract

A video display apparatus generates luminance information for individual frames of a video signal from histograms of the luminance component of the video signal, and classifies the content of the video signal on the basis of this information. Color saturation information is also generated from color saturation histograms, and scene changes are detected. Video correction parameters and display control parameters are derived from the content classification and color saturation information. The video signal is corrected according to the video correction parameters, and displayed according to the display control parameters. Display characteristics suitable for the video content are thereby obtained. The parameters are changed when a scene change is detected, so that the viewer is not disturbed by the change in video display characteristics.

Claims

1. A video display apparatus comprising:

a luminance information detector for receiving a video signal divided into frames, creating a luminance histogram from one frame of a luminance signal derived from the video signal, and generating luminance information from the luminance histogram;

a content classifier for classifying the content of the one frame according to the luminance information generated by the luminance information detector and generating a first classification value;

a content analyzer for analyzing the first classification values output by the content classifier for a plurality of frames to obtain a second classification value;

a saturation information detector for receiving the video signal, creating a color saturation histogram from at least one frame of a color saturation signal derived from the video signal, and generating color saturation information from the color saturation histogram;

a scene change detector for detecting scene changes in the video signal and generating a scene change detection signal;

a correction controller for outputting a video correction control signal and a display control signal, based on the second classification value, the scene change detection signal, and the color saturation information;

a video corrector for performing a video correction on the video signal, based on the video correction control signal; and

a display unit displaying a video picture according to the video signal output from the video corrector and performing display control according to the display control signal.

2. The video display apparatus of claim 1, wherein the luminance information detector generates maximum gradation information, intermediate gradation information, minimum gradation information, and average gradation information from the luminance histogram as the luminance information, and the content classifier classifies the video subject matter and generates the first classification value on the basis of the maximum gradation information, the intermediate gradation information, the minimum gradation information, and the average gradation information generated by the luminance information detector.

3. The video display apparatus of claim 1, further comprising a frame buffer for delaying the video signal by a positive integer number of frames, wherein the video corrector performs the video correction on the video signal delayed by the frame buffer.

4. The video display apparatus of claim 3, wherein the frame buffer compensates for delays occurring in the luminance information detector, the scene change detector, and the content analyzer.

5. The video display apparatus of claim 2, wherein:

the content classifier comprises a luminance decision unit that classifies luminance magnitudes and generates luminance decision values, and a classification decision unit that classifies the video content on the basis of the luminance decision values;

the scene change detector comprises a luminance decision unit that classifies luminance magnitudes and generates luminance decision values, and a scene change decision unit that determines scene changes from the luminance decision values; and

the luminance decision unit is shared by the content classifier and the scene change detector.

6. The video display apparatus of claim 2, wherein the scene change detector detects scene changes on the basis of the maximum gradation information, the intermediate gradation information, the minimum gradation information, and the average gradation information generated by the luminance information detector.

7. The video display apparatus of claim 1, wherein the correction controller computes the video correction control signal and the display control signal in a blanking interval during a scene change.

8. The video display apparatus of claim 1, wherein the video correction performed by the video corrector includes at least one of luminance contrast control, sharpness control, color depth control, three-dimensional noise reduction, and a gamma correction.

9. The video display apparatus of claim 1, wherein the display unit comprises a liquid crystal display panel with a backlight, and the display control performed by the display unit includes at least one of motion response control and backlight brightness control, motion response control being performed by overdriving.