Hierarchical Watermark Detector for Mobile Devices
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Solution Overview
Problem
Cellular phones and PDA devices face limitations in processor speed, memory, and system bandwidth, making it difficult to perform real-time detection of digital watermarks in large images due to their primitive operating systems and hardware constraints, which is a bottleneck for implementing sophisticated watermark detectors.
Innovation Solution
A block-based hierarchical watermark detector is developed that uses a search strategy to quickly locate the image region with the strongest watermark, reducing computational and data processing requirements, making it suitable for real-time software and low-cost hardware implementations by adapting watermark strength and using a hierarchical search algorithm.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a sophisticated watermark detector is implemented to achieve accurate detection results, then detection reliability is improved, but device complexity and computational requirements increase
Solution Approach 1:
The patent divides the image into multiple blocks and organizes them into a hierarchical structure with different resolution levels. The detector processes blocks at coarser levels first and progressively refines the search at finer levels, segmenting the detection task to reduce overall complexity while maintaining accuracy.
Solution Approach 2:
The patent introduces a hierarchical dimension to the detection process, organizing blocks across multiple resolution levels. This dimensional transformation allows the detector to operate on a simplified representation at coarse levels and only process detailed information at necessary finer levels, reducing computational burden.
2Speed
If real-time detection is performed on large images using conventional detectors, then detection speed is improved, but processor speed and memory requirements increase
Solution Approach 1:
The patent segments the image into blocks and processes them hierarchically, starting from coarser representations and refining only where necessary. This segmentation allows real-time detection on mobile devices by avoiding the need to process every pixel at full resolution simultaneously.
Solution Approach 2:
The detector performs partial processing by focusing computational resources only on regions where watermarks are likely present, rather than uniformly processing the entire image at full resolution. This selective processing enables real-time operation on devices with limited processing power.
3Measurement precision
If sophisticated watermark detection algorithms are used to improve detection accuracy, then measurement precision is improved, but system bandwidth and memory requirements increase
Solution Approach 1:
The patent segments the image data into blocks and processes them at different hierarchical levels. This segmentation allows the system to maintain high detection accuracy by focusing on relevant regions while reducing overall memory requirements by not loading or processing the entire high-resolution image at once.
Solution Approach 2:
The patent implements a nested hierarchical structure where blocks at finer resolution levels are contained within blocks at coarser levels. This nesting allows the system to store and process only the necessary detail levels, reducing memory footprint while preserving detection accuracy through the nested representation.
4Device complexity
If a hierarchical search strategy is implemented to reduce computational requirements, then device complexity is reduced, but search time may increase
Solution Approach 1:
The patent performs preliminary processing at coarser hierarchical levels to quickly identify regions of interest before proceeding to finer levels. This preliminary action filters out unlikely candidates early in the search process, reducing overall search time despite the additional hierarchical structure.
Solution Approach 2:
The hierarchical structure adds a resolution dimension to the search process, allowing the system to navigate through coarse-to-fine levels. This dimensional approach can reduce search time by avoiding exhaustive search at all levels simultaneously, as the hierarchy guides the search through likely regions first.
Data Source
AI summary
The present invention relates generally to digital watermarking. In one implementation, we provide a hierarchical digital watermark detector method. The method includes: i) in a first layer of a hierarchical search, performing watermark detection on blocks of at least a portion of an incoming suspect signal; ii) identifying a first block in the portion that is likely to include a decodable digital watermark; and iii) in a second layer of the hierarchical search, performing additional watermark detection on overlapping blocks in a neighborhood around the first block. Another implementation provides a hierarchical watermark detector including a buffer and a detector. The buffer stores portions of an incoming signal. The detector evaluates watermark detection criteria for blocks stored in the buffer, and hierarchically zooms into a neighborhood of blocks around a block associated with watermark detection criteria that satisfies detection criteria.