Display Apparatus Alternating Gamma Curves for Watermark Detection
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Solution Overview
Problem
Traditional watermarks in confidential documents can be obscured by similar hues or grayscale, making them difficult to read and detect, especially when they are not distinguishable from the surrounding information.
Innovation Solution
A display apparatus and method that alternately drives a watermark area and a non-watermark area using different gamma curves, creating a luminance difference of 0.2-0.6 between 10-90% grayscale values, making the watermark invisible to human eyes but detectable by photographic equipment.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If traditional watermarks are displayed with similar hue or grayscale to the confidential document, then the watermark is less obvious to human eyes, but the watermark becomes difficult to detect and read
Solution Approach 1:
The patent applies dynamic driving by alternately switching between first and second gamma curves for the watermark area at different time points. This dynamic adjustment creates temporal luminance variations that make watermarks detectable to photographic equipment while maintaining readability for human eyes, which perceive the averaged intermediate luminance.
Solution Approach 2:
The patent changes the luminance parameter by using different gamma curves (first gamma curve and second gamma curve) to drive the watermark area at different time points. The luminance difference percentage between these gamma curves is controlled within 0.2-0.6, creating detectable variations for photographic equipment while maintaining human readability.
2Measurement precision
If a watermark is made obvious to photographic equipment by using significant luminance difference, then the watermark is clearly detectable, but the watermark becomes noticeable and uncomfortable for human readers
Solution Approach 1:
The patent uses dynamic temporal switching between different gamma curves to create luminance variations that are detectable by photographic equipment but averaged out by human vision, maintaining reading comfort while achieving detection precision.
Solution Approach 2:
The patent implements periodic alternation between first and second gamma curves at different time points for the watermark area. This periodic action creates rhythmic luminance variations that photographic equipment can detect while human eyes perceive as stable intermediate luminance, preserving reading comfort.
3Measurement precision
If the luminance difference between gamma curves is increased to improve watermark detectability, then photographic equipment can capture the watermark more clearly, but the visual discomfort for human readers increases
Solution Approach 1:
The patent optimizes the luminance difference parameter by controlling the luminance difference percentage between first and second gamma curves within the range of 0.2-0.6. This parameter optimization ensures sufficient watermark detectability by photographic equipment while keeping visual discomfort for human readers within acceptable limits.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The approach ensures that human eyes perceive an intermediate luminance, while photographic equipment can clearly capture the watermark, effectively displaying the watermark without hindering readability.
Implementation Method 1
at least one of the watermark area and the non-watermark area is alternately driven by a first gamma curve and a second gamma curve
Implementation Method 2
Since human eye perception is equivalent to a luminance integrator, the human eyes may view an image with an intermediate luminance
Data Source
AI summary
A display apparatus and an image displaying method are provided. The display apparatus includes a display module and a driving circuit. The driving circuit is coupled to the display module and receives an input image. The driving circuit determines a watermark area and a non-watermark area of the display module according to watermark information, and at least one of the watermark area and the non-watermark area is alternately driven by a first gamma curve and a second gamma curve. A brightness difference percentage between the first gamma curve and the second gamma curve at a same grayscale value between 10% and 90% of a grayscale percentage is between 0.2 and 0.6.