Classifying method, storage medium, inspection method, and inspection apparatus

Patent metadata

Field	Value
Publication number	US-9959482-B2
Application number	US-201514945780-A
Country	US
Kind code	B2
Filing date	Nov 19, 2015
Priority date	Nov 28, 2014
Publication date	May 1, 2018
Grant date	May 1, 2018

Abstract

The present invention provides a classifying method of classifying an article into one of a plurality of groups based on an image of the article, comprising determining an evaluation method for obtaining an evaluation value of an image by using at least some of sample images, obtaining evaluation values for the sample images by the determined evaluation method, changing the evaluation method so as to increase a degree of dissimilarity in an evaluation value range for sample images between the plurality of groups by changing a evaluation value of at least one sample image having a singular evaluation value among the sample images, obtaining an evaluation value for the image of the article using the changed evaluation method, and classifying the article into one of the plurality of groups based on the evaluation value for the image of the article.

First claim

What is claimed is:

1. A classifying method of classifying an article into one of a plurality of groups based on an evaluation value for an image of the article, the method comprising:
a creating step of creating, based on sample images, which are images of a plurality of samples each of which has already been classified into one of the plurality of groups, a list of at least one image feature estimated to have been used to classify each sample;
a determining step of determining an evaluation method for obtaining the evaluation value, the evaluation method using a feature amount of the at least one image feature included in the list as a parameter;
a first obtaining step of obtaining evaluation values for the sample images by the determined evaluation method;
a changing step of changing the evaluation method by changing in the list, so that an evaluation value of at least one sample image having a singular evaluation value among the sample images is changed, and a degree of dissimilarity in an evaluation value range for sample images between the plurality of groups is increased; and
a second obtaining step of obtaining the evaluation value for the image of the article based on the changed evaluation method, and classifying the article into one of the plurality of groups based on the obtained evaluation value for the image of the article.

2. The method according to claim 1 , wherein the changing step changes the evaluation method so that a change in the evaluation value of the at least one sample image is larger than an average of changes in evaluation values of the sample images.

3. The method according to claim 1 , wherein:
the plurality of groups include a first group and a second group, and
the at least one sample image is selected from sample images where an evaluation value range for sample images of the first group overlaps an evaluation value range for sample images of the second group.

4. The method according to claim 1 , wherein the changing step:
obtains a plurality of candidates of the evaluation method by repeating a process of changing the evaluation method so that the degree satisfies an allowable value; and
determines a candidate with a highest degree among the plurality of candidates as the evaluation method to be used for obtaining the evaluation value for the image of the article.

5. The method according to claim 4 , wherein the changing step is repeated a preset number of times so that the degree satisfies the allowable value.

6. The method according to claim 1 , wherein the first obtaining step extracts at least one feature amount from each of the sample images as the parameter to be used by the evaluation method, and an evaluation value for each of the sample images is obtained by substituting the at least one feature amount into the evaluation method.

7. The method according to claim 1 , wherein the changing step:
obtains the evaluation values for the sample images based on the changed evaluation method; and
determines a threshold of the evaluation value for classifying the article based on the evaluation values for the sample images obtained based on the changed evaluation method.

8. The method according to claim 7 , wherein the changing step determines the threshold in accordance with a target rate at which samples that should be classified into a predetermined group among the plurality of groups are classified into the predetermined group.

9. The method according to claim 1 , wherein the changing step displays information that represents, for each group, an evaluation value for each of the sample images.

10. The method according to claim 9 , wherein the information comprises a histogram of the evaluation values in each group.

11. The method according to claim 9 , wherein:
the plurality of groups comprises a first group and a second group, and
the information comprises a relation between sample images of the first group sorted by the evaluation values and a number of sample images in the second group having an evaluation value corresponding to an evaluation value of the sample images of the first group.

12. The method according to claim 9 , wherein the changing step specifies the at least one sample image based on the displayed information.

13. A non-transitory computer-readable storage medium storing a program for causing a computer to execute each step of a classifying method of classifying an article into one of a plurality of groups based on an evaluation value for an image of the article, the method comprising the steps of:
creating, based on sample images, which are images of a plurality of samples each of which has already been classified into one of the plurality of groups, a list of at least one image feature estimated to have been used to classify each sample;
determining an evaluation method for obtaining the evaluation value, the evaluation method using a feature amount of the at least one image feature included in the list as a parameter;
obtaining evaluation values for the sample images by the determined evaluation method;
changing the evaluation method by changing in the list, so that an evaluation value of at least one sample image having a singular evaluation value among the sample images is changed, and a degree of dissimilarity in an evaluation value range for sample images between the plurality of groups is increased; and
obtaining the evaluation value for the image of the article based on the changed evaluation method, and classifying the article into one of the plurality of groups based on the obtained evaluation value for the image of the article.

14. An inspection method of performing inspection of an article, the method comprising the steps of:
obtaining an image of the article by capturing the article; and
classifying the article into one of a plurality of groups using a classifying method,
wherein the classifying method is a method of classifying the article into one of the plurality of groups based on an evaluation value for the image of the article, and includes the steps of:
creating, based on sample images, which are images of a plurality of samples each of which has already been classified into one of the plurality of groups, a list of at least one image feature estimated to have been used to classify each sample;
determining an evaluation method for obtaining the evaluation value, the evaluation method using a feature amount of the at least one image feature included in the list as a parameter;
obtaining evaluation values for the sample images by the determined evaluation method;
changing the evaluation method by changing in the list, so that an evaluation value of at least one sample image having a singular evaluation value among the sample images is changed, and a degree of dissimilarity in an evaluation value range for sample images between the plurality of groups is increased; and

obtaining the evaluation value for the image of the article based on the changed evaluation method, and classifying the article into one of the plurality of groups based on the obtained evaluation value for the image of the article.

15. An inspection apparatus for performing inspection of an article, the apparatus comprising:
an image capturing device configured to obtain an image of the article by capturing the article; and
a processor configured to classify the article into one of a plurality of groups based on an evaluation value for the image of the article,
wherein the processor is configured to:
create, based on sample images, which are images of a plurality of samples each of which has already been classified into one of the plurality of gro

Assignees

• Canon Kk

Inventors

• Uemura Takanori
• Okuda Hiroshi

Classifications

• G06V10/7715

  Feature extraction, e.g. by transforming the feature space, e.g. multi-dimensional scaling [MDS]; Mappings, e.g. subspace methods · CPC title

• G06V10/764

  using classification, e.g. of video objects · CPC title

• G06F18/2132

  based on discrimination criteria, e.g. discriminant analysis · CPC title

• G06F18/2413

  based on distances to training or reference patterns · CPC title

• G06V10/446 Primary

  using Haar-like filters, e.g. using integral image techniques · CPC title