Feature Likelihood Correction for Rare Pattern Detection

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Solution Overview

Problem

Conventional object detection methods, such as AdaBoost, struggle with accurately distinguishing feature patterns that are rare in the learning dataset, leading to high weights for difficult images and incorrect feature outputs.

Innovation Solution

A recognition apparatus that calculates the likelihood of feature quantities based on weighted distributions, corrects output values for specific feature quantities with high weights and low learning image ratios, and sets corrected likelihoods for feature quantity association, enabling stable object detection even with rare feature patterns.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If the conventional AdaBoost method is used to improve discrimination performance by focusing on difficult images, then the weight for difficult images becomes large, but the detection accuracy deteriorates when rare feature patterns are input

Engineering Contradiction:
Improvediscrimination performanceVSAvoiddetection accuracy
Core Design Contradiction:
ReliabilityVSMeasurement precision

Solution Approach 1:

The patent applies local quality by differentiating the treatment of feature quantities based on their rarity. Common feature quantities use conventional weight calculation, while rare feature quantities (those appearing in fewer than a threshold number of learning images) undergo special correction to reduce their weight influence. This localized differentiation resolves the contradiction by allowing high weights for difficult common features while suppressing potentially erroneous high weights for rare features.

Inventive Principle:
Principle #3Local quality

Solution Approach 2:

The patent changes the parameter of feature quantity weight by introducing a correction mechanism. When a feature quantity is identified as rare, its weight is corrected using a formula that incorporates the count of learning images containing that feature. This parameter transformation converts potentially harmful high weights into appropriately scaled weights, improving detection accuracy for rare feature patterns while maintaining reliability for common features.

Inventive Principle:
Principle #35Parameter changes

2Reliability

If the weight for difficult images is increased to improve learning focus, then the output value of weak discriminator becomes extreme, but the stability of detection deteriorates

Engineering Contradiction:
Improvelearning focusVSAvoiddetection stability
Core Design Contradiction:
ReliabilityVSStability of the object's composition

Solution Approach 1:

The patent applies preliminary anti-action by proactively identifying rare feature quantities before they cause detection instability. The system pre-calculates the count of learning images containing each feature quantity and prepares correction values in advance. When rare features are detected, the pre-prepared correction mechanism immediately counteracts their extreme weight influence, preventing detection instability before it occurs.

Inventive Principle:
Principle #9Preliminary anti-action

Solution Approach 2:

The patent implements feedback by using the count of learning images containing each feature quantity as a feedback signal. This feedback information is fed back into the weight calculation process, where it modulates the weight assignment. The feedback loop ensures that feature quantities with low occurrence counts (rare features) receive adjusted weights, creating a self-regulating system that maintains detection stability while preserving learning focus.

Inventive Principle:
Principle #23Feedback

Data Source

PatentUS9135524B2Recognition apparatus, recognition method, and storage medium
Publication Date: 2015.09.15 CANON KK
  • US9135524B2 patent drawing
  • US9135524B2 patent drawing
  • US9135524B2 patent drawing

AI summary

A recognition apparatus includes a calculation unit configured to calculate likelihood of each feature quantity based on the weighted distribution of the feature quantity extracted from a plurality of learning images, a correction unit configured, if a ratio of a learning image to a specific feature quantity is equal to or smaller than a predetermined ratio and a weight for the specific feature quantity is greater than a predetermined value, to correct the value of likelihood of the specific feature quantity to lower the value based on the distribution, a setting unit configured to set the likelihood corrected by the correction unit in association with a feature quantity, and a discrimination unit to extract a feature quantity from an input image and discriminate whether the input image includes a predetermined object based on the likelihood associated with the feature quantity.