Display Driving Apparatus Gray Range Extension
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Solution Overview
Problem
Current display devices, such as LCDs, often have limited gray ranges in image signals, leading to reduced visibility, especially in motion pictures where rapid transitions between dark and bright images can make it difficult to recognize the image.
Innovation Solution
A driving apparatus for display devices that includes a gray range calculation unit, a conversion variable calculation unit, and an output signal generator to extend the gray range by calculating the minimum and maximum grays of an image signal, using a slope based on previous frame data, and linearly converting the image signal to improve visibility and prevent image distortion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the gray range of image signals is limited to a predetermined range, then the display device can operate within standard parameters, but visibility is reduced especially in motion pictures with rapid transitions between dark and bright images
Solution Approach 1:
The patent applies dynamics by making the gray range adaptive rather than fixed. The signal controller dynamically adjusts the gray range based on the content of each frame or field, calculating minimum and maximum gray values from the input image signal and applying linear conversion with variable slopes. This allows the display to adapt to different image conditions (dark scenes, bright scenes, motion pictures) while maintaining reliable visibility throughout.
Solution Approach 2:
The patent changes the parameter of gray range from a fixed predetermined value to a variable range determined by analyzing the input image signal. By calculating minimum gray (Min) and maximum gray (Max) values from each frame/field and using these to define the output gray range, the system optimizes visibility for different image contents including motion pictures with rapid luminance transitions.
2Reliability
If the gray range is extended dynamically based on frame content, then visibility and image quality are improved, but the complexity of the signal processing increases
Solution Approach 1:
The patent segments the image signal processing into distinct functional stages: (1) dividing the input signal into frame or field units, (2) calculating minimum and maximum gray values for each segment, (3) determining linear conversion parameters (slope and intercept) based on these extremes, and (4) applying the conversion to generate output signals. This segmentation makes the complex processing manageable and implementable through systematic steps.
Solution Approach 2:
The patent implements feedback by using the calculated minimum and maximum gray values from the input signal to dynamically determine the conversion parameters, which then feed back into the signal transformation process. The system continuously monitors the input signal characteristics and adjusts the gray range expansion accordingly, creating a closed-loop processing system that optimizes visibility while managing complexity through iterative adjustment.
Data Source
AI summary
The driving apparatus of a display device calculates a slope using a minimum gray, a maximum gray, a gray average of frame data in a current frame, and a gray average of frame data in a previous frame, and corrects and outputs the input frame data according to the slope, using frame data of one frame. As a result, a gray range of the input image signal can be extended, thereby improving visibility. Further, in a case of a motion picture, even when a difference of a gray range of images of adjacent frames is large, an original image is not distorted due to extension of a gray range. Also, even when noise is included in the input image signal, a gray range can be extended after removing the noise.