REGION EXTRACTION APPARATUS AND REGION EXTRACTION METHOD

• US 20100226574A1
• Filed: 02/25/2010
• Published: 09/09/2010
• Est. Priority Date: 03/04/2009
• Status: Active Grant

• Current Assignee: Fujifilm Corporation (Fujifilm Holdings Corporation)
• Original Assignee: Fujifilm Corporation (Fujifilm Holdings Corporation)
• Inventors: OMORI, Yusuke
• Granted Patent: US 8,620,076 B2
• Time in Patent Office: Days
• US Class Current: 382/170
• CPC Class Codes: G06V 10/25 Determination of region of interest [ROI] or a volume of interest [VOI]
• CPC Class Codes: G06V 10/507 Summing image-intensity values; Histogram projection analysis

Abstract

A region extraction apparatus, comprising:

• • an image acquisition device that acquires an image;
  • a temporary initial region specifying device that specifies a plurality of temporary initial regions in the acquired image;
  • a separation calculation device that calculates a separation that is an indicator indicating how much pixel values of all pixels of the inside of the specified temporary initial region and pixel values of all pixels of the outside of the region are different from each other, on each temporary initial region;
  • an initial region specifying device that specifies the temporary initial region having the highest calculated separation as an initial region; and
  • a region extraction device that performs a region extraction process on the basis of the specified initial region.

Claims

1. A region extraction apparatus, comprising:

an image acquisition device that acquires an image;

a temporary initial region specifying device that specifies a plurality of temporary initial regions in the acquired image;

a separation calculation device that calculates a separation that is an indicator indicating how much pixel values of all pixels of the inside of the specified temporary initial region and pixel values of all pixels of the outside of the region are different from each other, on each temporary initial region;

an initial region specifying device that specifies the temporary initial region having the highest calculated separation as an initial region; and

a region extraction device that performs a region extraction process on the basis of the specified initial region.

2. The region extraction apparatus according to claim 1, further comprising:

a device that performs a process of blurring the entire image acquired, wherein

the temporary initial region specifying device specifies a plurality of temporary initial regions in the image having been subjected to the process of blurring the entire image.

3. The region extraction apparatus according to claim 1, wherein

the separation calculation device includes:

a histogram generation device that generates a first normalized histogram whose abscissa represents the pixel values on the basis of the pixel values of all the pixels inside of the temporary initial region and a second normalized histogram whose abscissa represents the pixel values on the basis of the pixel values of all the pixels outside of the temporary initial region; and

a device that calculates a total sum of absolute values of differences between the first and second normalized histograms on a pixel value basis, as the separation.

4. The region extraction apparatus according to claim 1, wherein

the separation calculation device includes:

a device that creates probability distribution models of the pixel values of the inside and outside of the temporary initial region; and

a device that calculates the separation between the probability distribution model of the inside of the temporary initial region and the probability distribution model of the outside of the region.

5. The region extraction apparatus according to claim 1, wherein the pixel value is a value in an prescribed color space such as an RGB color space and an HSV color space.

6. The region extraction apparatus according to claim 1, wherein

the temporary initial region specifying device includes:

a point specifying device that specifies an arbitrary point in the acquired image; and

a region specifying device that specifies a prescribed region centered at the specified arbitrary point as the temporary initial region.

7. The region extraction apparatus according to claim 6, wherein the point specifying device specifies a center of the acquired image as the arbitrary point.

8. The region extraction apparatus according to claim 6, further comprising:

a device that detects an edge from the acquired image; and

a device that calculates the barycenter of the detected edge, wherein

the point specifying device specifies the barycenter of the calculated point group as the arbitrary point.

9. The region extraction apparatus according to claim 6, wherein the temporary initial region specifying device specifies rectangular regions or circular regions centered at the arbitrary point and varying in size as the plurality of the temporary initial regions.

10. The region extraction apparatus according to claim 1, wherein the region extraction device performs the region extraction using a graph cut algorithm.

11. A region extraction method, comprising the steps of:

a step of acquiring an image;

a step of specifying a plurality of temporary initial regions in the acquired image;

a step of calculating a separation that is an indicator indicating how much the inside and outside of the specified temporary initial region are different from each other, on each temporary initial region;

a step of specifying the temporary initial region having the highest calculated separation as an initial region; and

a step of performing a region extraction process on the basis of the specified initial region.

12. The region extraction method according to claim 11, wherein

the step of specifying the plurality of temporary initial regions includes:

(1) a step of specifying an arbitrary point in the acquired image;

(2) a step of specifying a prescribed region centered at the specified arbitrary point as the temporary initial region; and

(3) a step of specifying a region centered at the specified arbitrary point and different in size from the prescribed region as the temporary initial region.

13. The region extraction method according to claim 12, wherein

the step of specifying the plurality of temporary initial regions includes:

(4) a step of changing the arbitrary point; and

(5) a step of repeatedly performing the steps set forth in (2) to (4).

14. The region extraction method according to claim 12, further comprising, between the step of acquiring the image and the step of specifying the plurality of temporary initial regions in the acquired image:

(6) a step of specifying a plurality of points in the acquired image;

(7) a step of specifying a prescribed region centered at the specified point as the temporary initial region on each of the plurality of points; and

(8) a step of calculating the separation between the inside and outside of the temporary initial region on each temporary initial region specified on each of the plurality of points, wherein

the step (1) regards a center point of the temporary initial region having the largest separation calculated in the step (8) as the arbitrary point.

15. A programmable storage medium tangibly embodying a program of machine-readable instructions executable by a digital processing apparatus to perform the region extraction method according to claim 11.

16. A programmable storage medium tangibly embodying a program of machine-readable instructions executable by a digital processing apparatus to perform the region extraction method according to claim 12.

17. A programmable storage medium tangibly embodying a program of machine-readable instructions executable by a digital processing apparatus to perform the region extraction method according to claim 13.

18. A programmable storage medium tangibly embodying a program of machine-readable instructions executable by a digital processing apparatus to perform the region extraction method according to claim 14.