Deformed Document Analysis via Geometric Transformation Estimation
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Solution Overview
Problem
Existing methods for analyzing deformed structured documents, such as passports or invoices, require complex computational processes and grid projection systems, making them inefficient and costly.
Innovation Solution
A method that estimates geometric transformations between images of a deformed document and its model using point matching and local transformations, reducing computational load by analyzing regions of interest separately, and utilizing different wavelength bands for enhanced accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If grid projection systems are used to analyze deformed documents, then measurement precision is improved, but device complexity increases
Solution Approach 1:
The patent uses a reference image (copy) of the document in its undeformed state to compare against the deformed document image. By matching features between the reference image and the deformed image, the system calculates deformation without requiring physical grid projection systems, thus maintaining measurement precision while eliminating device complexity
Solution Approach 2:
The patent replaces the mechanical grid projection system with an image processing approach. Instead of physically projecting grids onto the document and capturing them, the system uses digital image matching and computational geometry to determine deformation, substituting mechanical hardware with software-based solutions
2Measurement precision
If many points of interest are matched for precise transformation correction, then measurement precision is improved, but computational load increases
Solution Approach 1:
The patent divides the document into multiple regions of interest and processes each region separately. By segmenting the overall transformation problem into smaller regional transformations, the system achieves precise deformation characterization while reducing the computational complexity compared to processing all points globally
Solution Approach 2:
The patent applies different transformation models to different regions of the document based on local deformation characteristics. Rather than applying a single global transformation, the system adapts the transformation approach to local conditions, improving precision while optimizing computational resources
Data Source
AI summary
The invention relates to a method for analyzing a structured document likely to be deformed from a first image and a second image of the document, comprising steps of:matching first points of interest extracted in the first image with second points of interest of a reference image showing a model of the document,estimation of a first geometric transformation taking account of deformations of the structured document shown in the first image relative to the model from the matches,determination of at least one first region to be analyzed in the first image, by projection of at least one reference region of the reference image by means of the first transformation,analysis of the content of the first determined region,matching third points of interest extracted in the second image with fourth points of interest extracted in the first image,estimation, from the matches made in the preceding step, of a second geometric transformation taking account of deformations of the document shown in the second image relative to the document shown in the first image,estimation of a third geometric transformation taking account of deformations of the document shown in one of the two images, called target image, relative to the first model shown in the reference image, the third transformation dependent on the second transformation,determination of at least one second region to be analyzed in the target image by projection of the reference region of the reference image by means of the third geometric transformation,analysis of the content of the second determined region.