Image processing apparatus, image processing method, and image processing program

• US 9,183,628 B2
• Filed: 06/19/2014
• Issued: 11/10/2015
• Est. Priority Date: 12/20/2011
• Status: Active Grant

• Current Assignee: Fujifilm Corporation (Fujifilm Holdings Corporation)
• Original Assignee: Fujifilm Corporation (Fujifilm Holdings Corporation)
• Inventors: Wang, Caihua
• Primary Examiner(s): CHANG, JON CARLTON
• Application Number:
  US14/309,482
• Publication Number:
  US 20140301623A1
• Time in Patent Office: 509 Days
• Field of Search: None
• US Class Current: 1/1
• CPC Class Codes: A61B 2576/00 Medical imaging apparatus involving image processing or analysis A61B1/00009, A61B6/52 and A61B8/52 take precedence; image processing per se G06T; details of algorithms for analysing medical images G06T7/0012
• CPC Class Codes: A61B 2576/026 for the brain
• CPC Class Codes: A61B 5/0042 for the brain
• CPC Class Codes: A61B 5/055 involving electronic [EMR] or nuclear [NMR] magnetic resonance, e.g. magnetic resonance imaging
• CPC Class Codes: A61B 6/501 for diagnosis of the head, e.g. neuroimaging or craniography
• CPC Class Codes: A61B 6/5235 combining images from the same or different ionising radiation imaging techniques, e.g. PET and CT
• CPC Class Codes: G06T 2207/10081 Computed x-ray tomography [CT]
• CPC Class Codes: G06T 2207/20021 Dividing image into blocks, subimages or windows
• CPC Class Codes: G06T 2207/30016 Brain
• CPC Class Codes: G06T 3/18 Image warping, e.g. rearranging pixels individually
• CPC Class Codes: G06T 7/0012 Biomedical image inspection
• CPC Class Codes: G06T 7/337 involving reference images or patches
• CPC Class Codes: G16H 30/40 for processing medical images, e.g. editing

Abstract

A first image and a second image are obtained; the amount of deformation of the first image is estimated by evaluating the degree of similarity between a deformed first image and the second image, using an evaluation function that evaluates the correlation between the distribution of corresponding pixel values within the two images; and an image, which is the first image deformed based on the estimated amount of deformation, is generated. The evaluation function evaluates the degree of similarity between the deformed first image and the second image, based on degrees of similarities of divided images that represent degrees of similarities among the distributions of pixel values of each pair of divided first images and divided second images, which respectively are images that the deformed first image is divided into and images that the second image is divided into, according to predetermined dividing conditions.

Claims

1. An image processing apparatus, comprising:

an image obtaining section that obtains a first image and a second image which are obtained by imaging the same subject at different timings;

an image deformation amount estimating section that estimates an amount of deformation of the first image by deforming the first image and evaluating the degree of similarity between the deformed first image and the second image using an evaluation function that evaluates the correlative properties between the distribution of pixel values within the deformed first image and the distribution of pixel values within the second image corresponding thereto; and

an image generating section that generates an image, which is the first image deformed based on the estimated amount of deformation;

the evaluation function evaluating the degree of similarity between the deformed first image and the second image, based on degrees of similarities of divided images that represent degrees of similarities among the distributions of pixel values of each pair of divided first images and divided second images, which respectively are a plurality of images that the deformed first image is divided into according to predetermined dividing conditions and a plurality of images that the second image is divided into such that they correspond to the divided first images; and

the dividing conditions dividing the deformed first image into a plurality of divided first images based on a predetermined first spatial parameter, and dividing the second image into a plurality of divided second images that correspond to the divided first images based on a second spatial parameter corresponding to the first spatial parameter.

2. An image processing apparatus as defined in claim 1, wherein:

the first spatial parameter represents the distance from a predetermined shape within the first image, and the second spatial parameter represents the distance from a shape within the second image corresponding to the predetermined shape.

3. An image processing apparatus as defined in claim 2, wherein:

the predetermined shape is a point; and

the dividing conditions are those that divide the first image for each range of the first spatial parameter according to the first spatial parameter, and divide the second image for each range of the second spatial parameter, which corresponds to the range of the first spatial parameter.

4. An image processing apparatus as defined in claim 1, wherein:

the first spatial parameter represents an angle with respect to a predetermined shape within the first image, and the second spatial parameter represents an angle with respect to a shape within the second image corresponding to the predetermined shape.

5. An image processing apparatus as defined in claim 4, wherein:

the predetermined shape is a predetermined axis within the first image;

the first spatial parameter represents an angle from the predetermined axis within the first image; and

the second spatial parameter represents an angle from an axis within the second image corresponding to the predetermined axis.

6. An image processing apparatus as defined in claim 1, wherein:

the evaluation function defines the degree of similarity between the deformed first image and the second image based on a total sum of the degrees of similarity among the divided images.

7. An image processing apparatus as defined in claim 1, wherein:

the evaluation function represents an amount of mutual information, in which the pixel values of the deformed first image and the pixel values of the second image are discrete random variables.

8. An image processing method to be executed by an image processing apparatus comprising an image obtaining section, an image deformation amount estimating section, and an image generating section, comprising:

obtaining a first image and a second image which are obtained by imaging the same subject at different timings;

estimating an amount of deformation of the first image by deforming the first image and evaluating the degree of similarity between the deformed first image and the second image using an evaluation function that evaluates the correlative properties between the distribution of pixel values within the deformed first image and the distribution of pixel values within the second image corresponding thereto; and

generating an image, which is the first image deformed based on the estimated amount of deformation;

the evaluation function evaluating the degree of similarity between the deformed first image and the second image, based on degrees of similarities of divided images that represent degrees of similarities among the distributions of pixel values of each pair of divided first images and divided second images, which respectively are a plurality of images that the deformed first image is divided into according to predetermined dividing conditions and a plurality of images that the second image is divided into such that they correspond to the divided first images; and

the dividing conditions dividing the deformed first image into a plurality of divided first images based on a predetermined first spatial parameter, and dividing the second image into a plurality of divided second images that correspond to the divided first images based on a second spatial parameter corresponding to the first spatial parameter.

9. A non transitory computer readable medium having an image processing program stored therein, the program causing a computer to function as:

an image obtaining section that obtains a first image and a second image which are obtained by imaging the same subject at different timings;

an image deformation amount estimating section that estimates an amount of deformation of the first image by deforming the first image and evaluating the degree of similarity between the deformed first image and the second image using an evaluation function that evaluates the correlative properties between the distribution of pixel values within the deformed first image and the distribution of pixel values within the second image corresponding thereto; and

an image generating section that generates an image, which is the first image deformed based on the estimated amount of deformation;

the evaluation function evaluating the degree of similarity between the deformed first image and the second image, based on degrees of similarities of divided images that represent degrees of similarities among the distributions of pixel values of each pair of divided first images and divided second images, which respectively are a plurality of images that the deformed first image is divided into according to predetermined dividing conditions and a plurality of images that the second image is divided into such that they correspond to the divided first images; and

the dividing conditions dividing the deformed first image into a plurality of divided first images based on a predetermined first spatial parameter, and dividing the second image into a plurality of divided second images that correspond to the divided first images based on a second spatial parameter corresponding to the first spatial parameter.