Image processing apparatus, computer-readable medium storing an image processing program, and image processing method

1. An image processing apparatus configured to detect a moving object in a moving image, the apparatus comprising:

a background generation unit configured to generate a background image of the moving image while updating the background image over time; and

a moving object detection unit configured to detect the moving object in the moving image over time based on the background image,

the background generation unit including:

a model derivation unit configured to derive a mixed distribution model for each pixel of interest, the mixed distribution model having one or more distribution models depending on a situation; and

a background value derivation unit configured to derive one or more background pixel values respectively corresponding to the one or more distribution models based on the mixed distribution model for each pixel of interest, and

wherein the model derivation unit is configured to

generate a new distribution model from pixel values of a plurality of pixels within a local region containing the pixel of interest in a first frame that is contained in the moving image, and

update the existing distribution model using a pixel value of the pixel of interest in a second frame that is contained in the moving image and that is different from the first frame.

2. The image processing apparatus according to claim 1 ,

wherein if the mixed distribution model is not present, the model derivation unit is configured to generate a new distribution model.

3. The image processing apparatus according to claim 1 ,

wherein if a pixel value of the pixel of interest in the first frame is not contained in any existing distribution model, the model derivation unit is configured to generate a new distribution model.

4. The image processing apparatus according to claim 2 ,

wherein if a pixel value of the pixel of interest in the first frame is not contained in any existing distribution model, the model derivation unit is configured to generate a new distribution model.

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

a display control unit configured to display a frame including the detected moving object.

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

a display control unit configured to display a frame including the detected moving object.

7. The image processing apparatus according to claim 3 , further comprising:

a display control unit configured to display a frame including the detected moving object.

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

a display control unit configured to display a frame including the detected moving object.

9. The image processing apparatus according to claim 5 ,

wherein if it is detected that the moving object is present in two frames that are contained in the moving image and that are close to each other, and a direction of an optical flow of the moving object between the two frames matches a direction of movement of the centroid of the moving object between the two frames, the display control unit is configured to exclude the moving object in one of the two frames from a display target.

10. The image processing apparatus according to claim 6 ,

wherein if it is detected that the moving object is present in two frames that are contained in the moving image and that are close to each other, and a direction of an optical flow of the moving object between the two frames matches a direction of movement of the centroid of the moving object between the two frames, the display control unit is configured to exclude the moving object in one of the two frames from a display target.

11. The image processing apparatus according to claim 7 ,

wherein if it is detected that the moving object is present in two frames that are contained in the moving image and that are close to each other, and a direction of an optical flow of the moving object between the two frames matches a direction of movement of the centroid of the moving object between the two frames, the display control unit is configured to exclude the moving object in one of the two frames from a display target.

12. The image processing apparatus according to claim 8 ,

wherein if it is detected that the moving object is present in two frames that are contained in the moving image and that are close to each other, and a direction of an optical flow of the moving object between the two frames matches a direction of movement of the centroid of the moving object between the two frames, the display control unit is configured to exclude the moving object in one of the two frames from a display target.

13. The image processing apparatus according to claim 5 , further comprising:

a setting unit configured to receive setting of a color of the moving object,

wherein the display control unit is configured to exclude the moving object having a color that is not similar to the set color from the display target.

14. The image processing apparatus according to claim 6 , further comprising:

a setting unit configured to receive setting of a color of the moving object,

wherein the display control unit is configured to exclude the moving object having a color that is not similar to the set color from the display target.

15. The image processing apparatus according to claim 7 , further comprising:

a setting unit configured to receive setting of a color of the moving object,

wherein the display control unit is configured to exclude the moving object having a color that is not similar to the set color from the display target.

16. The image processing apparatus according to claim 8 , further comprising:

a setting unit configured to receive setting of a color of the moving object,

wherein the display control unit is configured to exclude the moving object having a color that is not similar to the set color from the display target.

17. The image processing apparatus according to claim 5 , further comprising:

a receiving unit configured to receive setting of a size and/or a shape of the moving object,

wherein the display control unit is configured to exclude the moving object having a size and/or a shape that is not similar to the set size and/or shape from the display target.

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

a judgement unit configured to judge whether or not identical frames consecutively appear in the moving image,

wherein if it is judged that identical frames consecutively appear in the moving image, generation of the background image and detection of the moving object are omitted with respect to a part of the consecutive identical frames.

19. A non-transitory computer-readable medium storing an image processing program for detecting a moving object in a moving image, the program causing a computer to execute the steps of:

generating a background image of the moving image while updating the background image over time; and

detecting the moving object in the moving image over time based on the background image,

the step of generating the background image including the steps of:

deriving a mixed distribution model for each pixel of interest, the mixed distribution model having one or more distribution models depending on a situation; and

deriving one or more background pixel value respectively corresponding to the one or more distribution models based on the mixed distribution model for each pixel of interest, and

the step of deriving the mixed distribution model including the steps of:

generating a new distribution model from pixel values of a plurality of pixels within a local region containing the pixel of interest in a first frame that is contained in the moving image; and

updating the existing distribution model using a pixel value of the pixel of interest in a second frame that is contained in the moving image and that is different from the first frame.

20. An image processing method for detecting a moving object in a moving image, the method comprising the steps of:

generating a background image of the moving image while updating the background image over time; and

detecting the moving object in the moving image over time based on the background image,

the step of generating the background image including the steps of:

deriving a mixed distribution model for each pixel of interest, the mixed distribution model having one or more distribution models depending on a situation; and

deriving one or more background pixel values respectively corresponding to the one or more distribution models based on the mixed distribution model for each pixel of interest, and

the step of deriving the mixed distribution model including the steps of:

generating a new distribution model from pixel values of a plurality of pixels within a local region containing the pixel of interest in a first frame that is contained in the moving image; and

updating the existing distribution model using a pixel value of the pixel of interest in a second frame that is contained in the moving image and that is different from the first frame.