Multiple Barcode Detection via Spatial Modulation
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Solution Overview
Problem
Existing methods for detecting data in images are limited in distinguishing arbitrarily placed watermarks and fail to effectively prevent unauthorized copying, as they rely on alignment or synchronizing marks, which are not present in all encoded data sets.
Innovation Solution
A method is developed to decode multiple barcodes printed on a page by estimating and determining grids within a bitmap representation, using spatial modulation of dots to encode data, allowing for the detection of multiple dot patterns without alignment or synchronizing marks, and controlling a photocopier to prevent unauthorized copying based on decoded messages.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If alignment or synchronizing marks are used for detecting encoded data, then detection accuracy is improved, but the method cannot detect arbitrarily placed watermarks without such marks
Solution Approach 1:
The invention extracts and removes the dependency on alignment or synchronizing marks from the detection process. By using spatial modulation of dot patterns where each dot's position encodes data directly, the system eliminates the need for separate alignment marks, enabling detection of arbitrarily placed watermarks while maintaining detection accuracy through the redundant encoding scheme
Solution Approach 2:
The dot pattern encoding method serves multiple functions: it encodes data, provides its own positioning information through spatial modulation, and enables detection without requiring separate alignment marks. This universal approach allows the same mechanism to handle both data encoding and positioning, making the system adaptable to arbitrarily placed watermarks
2Reliability
If multiple watermarks with different characteristics are embedded to determine authenticity, then original document identification is improved, but the method cannot detect arbitrarily placed watermarks from copy attacks
Solution Approach 1:
The system performs preliminary encoding of multiple redundant data sets into the dot patterns before copying occurs. Each dot pattern contains pre-encoded authentication data that can be independently detected and verified, allowing the system to identify original documents and detect copy attacks even when watermarks are arbitrarily placed or modified
Solution Approach 2:
The detection system uses feedback from multiple independently detectable dot patterns to verify authenticity. By comparing decoded data from different spatial locations and verifying consistency against expected authentication codes, the system can distinguish original documents from copies regardless of how watermarks are placed or modified
3Reliability
If fixed patterns or indicia are used to prevent unauthorized copying, then copy prevention is achieved, but the method relies on specific pattern recognition that may fail with modified copies
Solution Approach 1:
The invention changes the encoding parameters from fixed patterns to spatially modulated dot patterns where data is encoded in the relative positions of dots. This parameter change makes the encoding more robust because it can tolerate variations in absolute position, scaling, and minor distortions that occur during copying, while still maintaining reliable copy prevention through authentication verification
Data Source
AI summary
Disclosed is a method of decoding a first barcode and a second barcode, different from the first barcode. The barcodes have typically been printed on a page and are derived from image scanning. The first barcode comprises a plurality of marks modulated about a first grid to redundantly encode data and the second barcode comprising a plurality of marks modulated about a second grid. The method estimates (810) the first grid from a bitmap representation (805) of at least a portion of the page, using modulated marks contained therein. The method determines (820) a first barcode region from the first grid, the first barcode region being a portion of the first barcode, followed by estimating a second grid from the bitmap representation, using modulated marks contained therein. The method determines a second barcode region from the second grid, the second barcode region being a portion of the second barcode, and then decodes (830) the first and second barcode regions using the first and second grids respectively to derive the first and second barcodes.