Multi-Stage Image Mapping Mechanism for Homography Rectification

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Solution Overview

Problem

Conventional image mapping techniques for rectifying homographic distortions are computationally expensive and inefficient in terms of memory access, as they require independent identification of corresponding pixels in distorted and rectified images, leading to increased computational complexity and time consumption.

Innovation Solution

A multi-stage image mapping mechanism that decomposes the homography transformation into two separate transformations, allowing for efficient pixel correspondence identification and memory access by mapping pixels in a distorted image to a rectified image through a two-stage process, where the first stage removes partial distortion to generate an intermediate image and the second stage removes residual distortion to produce a rectified image.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If conventional image mapping techniques are used to rectify homographic distortions, then accurate pixel correspondence can be achieved, but computational complexity and computing time increase significantly

Engineering Contradiction:
Improvepixel correspondence accuracyVSAvoidcomputational complexity
Core Design Contradiction:
Measurement precisionVSDevice complexity

Solution Approach 1:

The patent segments the image mapping process into distinct stages: identifying anchor pixels, computing transformation parameters, and applying the transform to remaining pixels. This segmentation allows the complex homographic rectification to be broken down into manageable steps, reducing overall computational complexity while maintaining accuracy through systematic processing

Inventive Principle:
Principle #1Segmentation

2Measurement precision

If conventional image mapping techniques are used to rectify homographic distortions, then accurate pixel correspondence can be achieved, but computing time increases significantly

Engineering Contradiction:
Improvepixel correspondence accuracyVSAvoidcomputing time
Core Design Contradiction:
Measurement precisionVSLoss of time

Solution Approach 1:

The patent performs preliminary actions by pre-identifying anchor pixels and pre-computing transformation parameters before applying the full transform. This preliminary computation of key reference points enables faster processing of the remaining pixels, reducing overall computing time while maintaining accuracy

Inventive Principle:
Principle #10Preliminary action

Solution Approach 2:

The patent uses anchor pixels as reference copies that define the transformation. Once the transform parameters are computed from anchor pixels, these parameters are copied and applied to transform all other pixels, avoiding redundant computation for each individual pixel while maintaining consistent accuracy

Inventive Principle:
Principle #26Copying

3Measurement precision

If independent pixel identification is performed for each pixel, then accurate mapping can be achieved, but memory access efficiency deteriorates

Engineering Contradiction:
Improvemapping accuracyVSAvoidmemory access efficiency
Core Design Contradiction:
Measurement precisionVSProductivity

Solution Approach 1:

The patent merges the transformation operation into a unified process where a single homographic transform parameter set is applied to all pixels simultaneously. This combining of the transform operation allows for optimized memory access patterns, as pixels can be processed in batches or sweeps rather than independent random accesses, improving memory access efficiency while maintaining mapping accuracy

Inventive Principle:
Principle #5Merging (Combining)

Data Source

PatentUS9542732B2Efficient image transformation
Publication Date: 2017.01.10 COGNEX CORP
  • US9542732B2 patent drawing
  • US9542732B2 patent drawing
  • US9542732B2 patent drawing

AI summary

The present disclosure provides a multi-stage image mapping mechanism for mapping a distorted image to a rectified image. For example, the multi-stage image mapping mechanism can remove homography from a distorted image to reconstruct a rectified image in two-stages: (1) a first stage in which distortion is partially removed from a distorted image to generate an intermediate image, and (2) a second stage in which residual distortion is removed from the intermediate image to recover the rectified image.