Object Distance Estimation Using Modulation Transfer Function

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Solution Overview

Problem

Conventional imaging systems require substantial calculation time to determine the distance of an object and improve image sharpness due to the need to deconvolute images with multiple point spread functions, which is inefficient and resource-intensive.

Innovation Solution

The method involves estimating the modulation transfer function, determining aberration frequencies, performing principal component analysis, and using a joint distribution of probability densities between principal components and object-system distances to quickly determine the object's distance, allowing for efficient selection of the optimal point spread function for image deconvolution.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If deconvolution is performed with multiple point spread functions to determine object distance and improve image sharpness, then image quality is improved, but calculation time increases substantially

Engineering Contradiction:
Improveimage sharpnessVSAvoidcalculation time
Core Design Contradiction:
Measurement precisionVSLoss of time

Solution Approach 1:

The patent pre-calculates and stores the modulation transfer function for multiple object distances before actual image processing. During operation, the system only needs to retrieve the pre-computed MTF corresponding to the estimated object distance, avoiding the need to perform complex deconvolution calculations with multiple point spread functions in real-time, thus significantly reducing calculation time while maintaining image quality

Inventive Principle:
Principle #10Preliminary action

Solution Approach 2:

The patent creates a lookup table that copies and stores pre-computed modulation transfer functions for various object distances. Instead of performing computationally intensive deconvolution operations with multiple point spread functions during actual imaging, the system retrieves the appropriate pre-computed MTF from the lookup table, substantially reducing the time required for distance determination and image processing

Inventive Principle:
Principle #26Copying

2Measurement precision

If deconvolution is performed with multiple point spread functions to determine object distance, then distance measurement accuracy is improved, but computational resources required increase substantially

Engineering Contradiction:
Improvedistance measurement accuracyVSAvoidcomputational resources
Core Design Contradiction:
Measurement precisionVSDevice complexity

Solution Approach 1:

The patent extracts the essential distance information from the complex deconvolution process by using the modulation transfer function, which captures the optical system's response characteristics. By analyzing the MTF's frequency response patterns, the system can determine object distance without performing computationally intensive deconvolution operations with multiple point spread functions, thus reducing computational resource requirements while maintaining distance measurement accuracy

Inventive Principle:
Principle #2Taking out (Extraction)

Solution Approach 2:

The patent replaces the computationally intensive mechanical process of deconvolution with multiple point spread functions with a more efficient signal processing approach using the modulation transfer function. The MTF-based method substitutes complex iterative deconvolution calculations with simpler frequency-domain analysis, reducing the computational resources needed for distance determination while maintaining measurement precision

Inventive Principle:
Principle #28Mechanics substitution (Replace mechanical system)

Data Source

PatentUS9964405B2Method for estimating the distance of an object from an imaging system
Publication Date: 2018.05.08 IDEMIA IDENTITY & SECURITY FRANCE SAS

AI summary

The invention relates to a method, for determining a distance between an object with respect to an imaging system, improving the reconstruction of images of objects imaged by an imaging system and improving the resolution of the images obtained.