OSD Circuit Intermediate Layer Visibility
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Solution Overview
Problem
In image display systems, On-Screen Display (OSD) characters often suffer from poor visibility due to differences in color and brightness with the underlying image data, leading to visibility degradation.
Innovation Solution
A semiconductor apparatus with an OSD circuit that inserts an intermediate layer with alpha blending, allowing for improved visibility of OSD characters by generating alpha-value distributions and using a separation color, which can be embedded in the OSD character's bitmap data, reducing memory requirements and supporting various OSD character sizes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If OSD characters are overlaid directly on image data, then the OSD function can be implemented with simple structure, but the visibility of OSD characters degrades due to color and brightness differences with the background
Solution Approach 1:
An intermediate layer is introduced between the image data and OSD characters. This intermediate layer has a different color from both the image data background and the OSD characters, serving as a mediator to improve visibility. The intermediate layer is generated by alpha blending the image data with a predetermined color at alpha values less than 255, creating a semi-transparent effect that enhances contrast.
Solution Approach 2:
The color parameters of the display are modified by introducing the intermediate layer with a predetermined color that differs from both the background and OSD characters. By controlling the alpha values (0-255) of the intermediate layer, the visibility parameters are dynamically adjusted to optimize contrast and readability.
2Reliability
If visibility detection function is added to detect color and brightness differences, then OSD character visibility can be improved, but the device complexity increases
Solution Approach 1:
Instead of detecting visibility issues and then correcting them, the solution performs preliminary action by proactively generating an intermediate layer with optimized alpha values before OSD characters are displayed. This prevents visibility degradation from occurring in the first place, eliminating the need for complex detection and correction mechanisms.
Solution Approach 2:
The intermediate layer serves as a mediator that simplifies the overall structure by providing a built-in visibility enhancement mechanism, replacing the need for separate detection and correction circuits.
3Quantity of substance
If bitmap data of OSD characters is stored in external ROM, then memory capacity is sufficient, but the system requires external components increasing complexity
Solution Approach 1:
The patent merges the ROM function into the timing controller by integrating a memory unit directly within the timing controller circuitry. This allows bitmap data of OSD characters to be stored internally, eliminating the need for external ROM components while maintaining sufficient memory capacity.
Solution Approach 2:
The timing controller is designed with multi-functionality, serving both as a control device and as a storage device for OSD character bitmap data. This universal design reduces the total number of components in the system.
Data Source
AI summary
A video input interface receives video data. An OSD circuit draws an intermediate layer in a target region in which an OSD character is to be overlaid on the video data, and overlays the OSD character on the intermediate layer.