Region extraction apparatus and region extraction method

• US 8,620,076 B2
• Filed: 02/25/2010
• Issued: 12/31/2013
• Est. Priority Date: 03/04/2009
• Status: Expired due to Fees

• Current Assignee: Fujifilm Corporation (Fujifilm Holdings Corporation)
• Original Assignee: Fujifilm Corporation (Fujifilm Holdings Corporation)
• Inventors: Omori, Yusuke
• Primary Examiner(s): Thirugnanam, Gandhi
• Application Number:
  US12/712,465
• Publication Number:
  US 20100226574A1
• Time in Patent Office: 1,405 Days
• Field of Search: 382/171
• US Class Current: 382/171
• 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 includes 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 an inside of a specified temporary initial region and pixel values of all pixels of an outside of the specified temporary region are different from each other, on each temporary initial region, an initial region specifying device that specifies a temporary initial region having a highest calculated separation as an initial region, and a region extraction device that performs a region extraction on a 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 an inside of a specified temporary initial region and pixel values of all pixels of an outside of the specified temporary region are different from each other, on each temporary initial region;

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

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

wherein the separation calculation device includes;

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

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

a device that performs a blurring of image acquired,

wherein the temporary initial region specifying device specifies the plurality of temporary initial regions in an image subjected to the blurring of the image.

3. The region extraction apparatus according to claim 1, wherein the separation calculation device further 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.

4. The region extraction apparatus according to claim 1, wherein the pixel value comprises a value in an RGB color space or an HSV color space.

5. 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.

6. The region extraction apparatus according to claim 5, wherein the point specifying device specifies a center of the acquired image as the arbitrary point.

7. The region extraction apparatus according to claim 5, further comprising:

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

a device that calculates a barycenter of the detected edge,

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

8. The region extraction apparatus according to claim 5, 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.

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

10. A region extraction method, comprising:

acquiring an image;

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

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

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

performing a region extraction on a basis of the specified initial region,

wherein the calculating of the separation includes;

generating a first normalized histogram whose abscissa represents the pixel values on a basis of pixel values of all the pixels inside of the specified temporary initial region and a second normalized histogram whose abscissa represents pixel values on a basis of the pixel values of all the pixels outside of the specified temporary initial region; and

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

11. The region extraction method according to claim 10, wherein the specifying the plurality of temporary initial regions includes:

specifying an arbitrary point in the acquired image;

specifying a prescribed region centered at the specified arbitrary point as the temporary initial region; and

specifying a region centered at the specified arbitrary point and different in size from the prescribed region as the temporary initial region.

12. The region extraction method according to claim 11, wherein the specifying the plurality of temporary initial regions further includes:

changing the arbitrary point; and

repeatedly performing the specifying the prescribed region, the specifying the region, and the changing the arbitrary point.

13. The region extraction method according to claim 11, further comprising, between the acquiring the image and the specifying the plurality of temporary initial regions in the acquired image:

specifying a plurality of points in the acquired image;

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

calculating the separation between the inside and the outside of the temporary initial region on each temporary initial region specified on each of the plurality of points,

wherein the specifying an arbitrary point regards a center point of the temporary initial region having a largest separation calculated in the calculating the separation between the inside and the outside of the temporary initial region as the arbitrary point.

14. A non-transitory computer readable storage medium tangibly embodying a program of machine-readable instructions executable by a digital processing apparatus to perform a region extraction method, the method comprising:

acquiring an image;

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

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

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

performing a region extraction on a basis of the specified initial region,

wherein the calculating of the separation includes;

generating a first normalized histogram whose abscissa represents pixel values on a basis of the pixel values of all the pixels inside of the specified temporary initial region and a second normalized histogram whose abscissa represents pixel values on a basis of the pixel values of all the pixels outside of the specified temporary initial region; and

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

15. The non-transitory computer readable storage medium tangibly embodying the program of machine-readable instructions executable by the digital processing apparatus to perform the region extraction method according to claim 14, wherein the specifying the plurality of temporary initial regions includes:

specifying an arbitrary point in the acquired image;

specifying a prescribed region centered at the specified arbitrary point as the temporary initial region; and

specifying a region centered at the specified arbitrary point and different in size from the prescribed region as the temporary initial region.

16. The non-transitory computer readable storage medium tangibly embodying the program of machine-readable instructions executable by the digital processing apparatus to perform the region extraction method according to claim 15, wherein the specifying the plurality of temporary initial regions further includes:

changing the arbitrary point; and

repeatedly performing the specifying the prescribed region, the specifying a region, and the changing the arbitrary point.

17. The non-transitory computer readable storage medium tangibly embodying the program of machine-readable instructions executable by the digital processing apparatus to perform the region extraction method according to claim 15, wherein the method further comprises, between the acquiring the image and the specifying the plurality of temporary initial regions in the acquired image:

specifying a plurality of points in the acquired image;

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

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 specifying an arbitrary point regards a center point of the temporary initial region having a largest separation calculated in the calculating the separation between the inside and outside of the temporary initial region as the arbitrary point.