Similar-image retrieving apparatus, similar-image retrieving method and program storage medium

• US 6,249,607 B1
• Filed: 09/16/1998
• Issued: 06/19/2001
• Est. Priority Date: 09/19/1997
• Status: Expired due to Term

• Current Assignee: Minolta Co., Ltd. (Konica Minolta Inc.)
• Original Assignee: Minolta Co., Ltd. (Konica Minolta Inc.)
• Inventors: Murakawa, Akira
• Primary Examiner(s): Johns, Andrew W.
• Assistant Examiner(s): Azarian, Seyed H.
• Application Number:
  US09/153,850
• Time in Patent Office: 1,007 Days
• Field of Search: 382/199, 382/198, 382/200, 382/201, 382/208, 382/209, 382/218, 382/219, 382/220, 382/221, 382/280, 382/279, 382/281, 382/278
• US Class Current: 382/199
• CPC Class Codes: G06V 10/431 Frequency domain transformation; Autocorrelation

Abstract

A similar-image retrieving apparatus and a similar-image retrieving method allow data amount to be reduced by digitizing feature quantities of external shapes of islands extracted from images, and also allow shape comparison to be achieved by simple calculation of the digitized feature quantities. Thus, the apparatus and the method are capable of practical retrieval of similar images. A feature quantity extracting section 2 extracts an external shape of an island from image data, and determines coefficients by Fourier series expansion of point strings of edge pixels of the external shape, thereby extracting the coefficients as feature quantities of the external shape of the island. Based on the feature quantities of a key image and the feature quantities of comparative images extracted in this way by the feature quantity extracting section 2, similarities between the key image and the comparative images are calculated by a similarity calculating section 6.

Claims

1. An image processing apparatus for extracting features of an image from digital image data of the image, comprising:

a detection controller for extracting an external shape of an island from an image and detecting coordinates of a pixel string positioned at an edge portion of the external shape; and

an extraction controller for extracting, as feature information of the image, coefficients determined by Fourier series expansion of the coordinates of the pixel string detected by the detection controller.

2. The image processing apparatus according to claim 1, further comprising

a calculation controller for comparing the feature information of the image extracted by the extraction controller with feature information of a specified image and calculating a similarity between the two images.

3. The image processing apparatus according to claim 2, wherein

the calculation controller calculates the similarity by multiplying coefficients for selected orders of the Fourier series by respective weights.

4. The image processing apparatus according to claim 1, further comprising:

a registration controller for registering in a database the feature information extracted by the extraction controller in association with the image data of the image; and

a retrieval controller for retrieving desired image data based on the feature information from among the image data registered in the database by the registration controller.

5. The image processing apparatus according to claim 4, wherein

the retrieval controller comprises:

an input device for receiving feature information of an image which serves as a key to retrieval; and

a calculation controller for comparing feature information of a plurality of images registered in the database with the feature information received by the input device and calculating similarities between the plurality of images and the key image so that the retrieval controller retrieves image data based on results of the calculation.

6. An image processing method for extracting features of an image from digital image data of the image, comprising:

a detection step for extracting an external shape of an island from an image and detecting coordinates of a pixel string positioned at an edge portion of the external shape; and

an extraction step for extracting, as feature information of the image, coefficients determined by Fourier series expansion of the coordinates of the pixel string detected by the detection step.

7. The image processing method according to claim 6, further comprising

a calculation step for comparing the feature information of the image extracted by the extraction step with feature information of a specified image and calculating a similarity between the two images.

8. The image processing method according to claim 7, wherein

in the circulation step, the similarity is calculated by multiplying coefficients for selected orders of the Fourier series by respective weights.

9. The image processing method according to claim 6, further comprising:

a registration step for registering in a database the feature information extracted by the extraction step in association with the image data of the image; and

a retrieval step for retrieving desired image data based on the feature information from among the image data registered in the database by the registration step.

10. The image processing method according to claim 9, wherein

the retrieval step comprises:

an input step for receiving feature information of an image which serves as a key to retrieval; and

a calculation step for comparing feature information of a plurality of images registered in the database with the feature information received by the input step, calculating similarities between the plurality of images and the key image so that the retrieval step retrieves image data based on results of the calculation.

11. A computer program product in a memory for executing image processing to extract features of an image from digital image data of the image, comprising:

a detection control for extracting an external shape of an island from an image and detecting coordinates of a pixel string positioned at an edge portion of the external shape; and

an extraction control for extracting, as feature information of the image, coefficients determined by Fourier series expansion of the coordinates of the pixel string detected by the detection control.

12. The computer program product according to claim 11, further comprising

a calculation control for comparing the feature information of the image extracted by the extraction control with feature information of a specified image and calculating a similarity between the two images.

13. The computer program product according to claim 12, wherein

the calculation control calculates the similarity by multiplying coefficients for selected orders of the Fourier series by respective weights.

14. The computer program product according to claim 11, further comprising

a registration control for registering in a database the feature information extracted by the extraction control in association with image data of the image;

and

a retrieval control for retrieving desired image data based on the feature information from among the image data registered in the database by the registration control.

15. The computer program product according to claim 14, wherein

the retrieval control comprises:

an input device for receiving feature information of an image which serves as a key to retrieval; and

a calculation control for comparing feature information of a plurality of images registered in the database with the feature information received by the input device, calculating similarities between the plurality of images and the key image so that the retrieval control retrieves image data based on results of the calculation.