SYSTEM AND METHOD FOR CORRECTING IMAGE THROUGH ESTIMATION OF DISTORTION PARAMETER

• US 20200134789A1
• Filed: 10/08/2019
• Published: 04/30/2020
• Est. Priority Date: 10/31/2018
• Status: Active Grant

• Current Assignee: Industry-University Cooperation Foundation Hanyang University
• Original Assignee: Industry-University Cooperation Foundation Hanyang University
• Inventors: PAIK, Joonki, LEE, Minjung, KIM, Hyungtae
• Granted Patent: US 11,164,292 B2
• Time in Patent Office: Days
• CPC Class Codes: G06T 2207/30201 Face
• CPC Class Codes: G06T 5/80 Geometric correction
• CPC Class Codes: G06V 40/171 Local features and components; Facial parts eye characteristics G06V40/18; Occluding parts, e.g. glasses; Geometrical relationships

Abstract

Provided are a system and method for correcting an image through estimation of a distortion parameter. The method includes receiving a distorted image including one or more measurement targets, extracting a plurality of feature points from each of the measurement targets, classifying the one or more measurement targets as a distorted target and an undistorted target by comparing distances between the plurality of extracted feature points and a center point of the received distorted image with each other, estimating a distortion parameter on the basis of standard deviations of a plurality of feature points of the classified distorted target and undistorted target, and correcting the received distorted image on the basis of the estimated distortion parameter.

Claims

1. A system for correcting an image through estimation of a distortion parameter, the system comprising:

a distorted image receiver configured to receive a distorted image including one or more measurement targets;

a feature point extractor configured to extract a plurality of feature points from each of the measurement targets;

a feature point classifier configured to compare distances between the plurality of extracted feature points and a center point of the received distorted image with each other and classify the one or more measurement targets as a distorted target and an undistorted target;

a distortion parameter estimator configured to estimate a distortion parameter on the basis of standard deviations of a plurality of feature points of the classified distorted target and undistorted target; and

an image corrector configured to correct the received distorted image on the basis of the estimated distortion parameter.

2. The system of claim 1, further comprising:

an iterative corrector configured to output one or more repeatedly-corrected images by repeatedly estimating the distortion parameter and repeatedly correcting the corrected image until the corrected image satisfies a preset condition; and

a final corrected-image selector configured to detect straight-line information including a number and length of straight lines in the one or more output images and select a final corrected image on the basis of the straight-line information.

3. The system of claim 1, wherein the one or more measurement targets are people, and

the plurality of feature points include a center point of an eye corresponding to an iris of a corresponding person'"'"'s left eye, a center point of an eye corresponding to an iris of the corresponding person'"'"'s right eye, an end point of the corresponding person'"'"'s nose, a left end point of the corresponding person'"'"'s mouth, and a right end point of the corresponding person'"'"'s mouth.

4. The system of claim 3, wherein the feature point classifier classifies the one or more measurement targets as a distorted target and an undistorted target according to undistorted-target standard formulae given by Equations 8 and 9 below:

5. The system of claim 1, wherein the distortion parameter estimator calculates the distortion parameter to be estimated according to a distortion parameter formula given by Equation 10 below:

6. The system of claim 2, wherein the iterative corrector repeatedly corrects the corrected image according to iterative correction formulae given by Equations 11 and 12 below:

7. The system of claim 2, wherein the iterative corrector and the final corrected-image selector operate according to a cost function given by Equation 14 below:

8. A method of correcting an image through estimation of a distortion parameter, the method comprising:

a distorted image receiving operation of receiving, by a distorted image receiver, a distorted image including one or more measurement targets;

a feature point extraction operation of extracting, by a feature point extractor, a plurality of feature points from each of the measurement targets;

a feature point classification operation of comparing, by a feature point classifier, distances between the plurality of extracted feature points and a center point of the received distorted image with each other and classifying the one or more measurement targets as a distorted target and an undistorted target;

a distortion parameter estimation operation of estimating, by a distortion parameter estimator, a distortion parameter on the basis of standard deviations of a plurality of feature points of the classified distorted target and undistorted target; and

an image correction operation of correcting, by an image corrector, the received distorted image on the basis of the estimated distortion parameter.

9. The method of claim 8, further comprising:

an iterative correction operation of repeatedly estimating, by an iterative corrector, the distortion parameter and repeatedly correcting the corrected image until the corrected image satisfies a preset condition and outputting one or more repeatedly-corrected images; and

a final corrected-image selection operation of detecting, by a final corrected-image selector, straight-line information including a number and length of straight lines in the one or more output images and selecting a final corrected image on the basis of the straight-line information.

10. The method of claim 8, wherein the one or more measurement targets are people, and

the plurality of feature points include a center point of an eyes corresponding to an iris of a corresponding person'"'"'s left eye, a center point of an eye corresponding to an iris of the corresponding person'"'"'s right eye, an end point of the corresponding person'"'"'s nose, a left end point of the corresponding person'"'"'s mouth, and a right end point of the corresponding person'"'"'s mouth.

11. The method of claim 10, wherein the feature point classification operation comprises classifying the one or more measurement targets as a distorted target and an undistorted target according to undistorted-target standard formulae given by Equations 8 and 9 below:

12. The method of claim 8, wherein the distortion parameter estimation operation comprises calculating the distortion parameter to be estimated according to a distortion parameter formula given by Equation 10 below:

13. The method of claim 9, wherein the iterative correction operation comprises repeatedly correcting the corrected image according to iterative correction formulae given by Equations 11 and 12 below:

14. The method of claim 9, wherein the final corrected-image selection operation comprises causing the iterative corrector and the final corrected-image selector to operate according to a cost function given by Equation 14 below: