Image processing apparatus, method, and program

1. An image processing apparatus, comprising:

3-value image generating means for generating a 3-value image made up of first through third values from a 2-value image, wherein the 2-value image is made up of a first value indicating, on a per-pixel basis, a foreground image region in an input image, as well as a second value similarly indicating a background image region, and wherein the third value of the 3-value image indicates an unknown region defined differently from both the foreground image region and the background image region such that the unknown region is defined having a predetermined width at the boundary between the foreground image region and the background image region;

ratio image generating means for generating a ratio image from the input image and the 3-value image, wherein the ratio image is made up of a fourth value that indicates, on a per-pixel basis, the ratio of the first value;

updating means for updating the 3-value image by defining a predetermined range near a pixel in the 3-value image that corresponds to a pixel in the ratio image whose fourth value is greater than a minimum value and less than a maximum value, and setting all pixels within the defined range to the third value;

determining means for determining whether or not the 3-value image updated by the updating means is identical or nearly identical to the 3-value image before being updated by the updating means; and

output means for outputting the updated 3-value image if it is determined that the 3-value image updated by the updating means is identical or nearly identical to the 3-value image before being updated by the updating means.

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

expansion amount defining means for defining, on a per-pixel basis, a range near a pixel in the 3-value image that corresponds to a pixel in the ratio image whose fourth value is greater than a minimum value and less than a maximum value, the range being defined in the form of an expansion amount;

wherein the updating means updates the 3-value image by setting all pixels within a predetermined range to the third value, the predetermined range being that defined by the expansion amount near a pixel in the 3-value image that corresponds to a pixel in the ratio image whose fourth value is greater than a minimum value and less than a maximum value.

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

expansion direction defining means for defining, on a per-pixel basis, a range near a pixel in the 3-value image that corresponds to a pixel in the ratio image whose fourth value is greater than a minimum value and less than a maximum value, the range being defined in the form of an expansion direction;

wherein the updating means updates the 3-value image by setting all pixels within a predetermined range to the third value, the predetermined range being that defined by the expansion direction near a pixel in the 3-value image that corresponds to a pixel in the ratio image whose fourth value is greater than a minimum value and less than a maximum value.

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

expansion vector defining means for defining, on a per-pixel basis, a range near a pixel in the 3-value image that corresponds to a pixel in the ratio image whose fourth value is greater than a minimum value and less than a maximum value, the range being defined in the form of an expansion vector made up of an expansion direction and an expansion amount;

wherein the updating means updates the 3-value image by setting all pixels within a predetermined range to the third value, the predetermined range being that defined by the expansion vector near a pixel in the 3-value image that corresponds to a pixel in the ratio image whose fourth value is greater than a minimum value and less than a maximum value.

5. The image processing apparatus according to claim 4 , wherein the expansion direction of the expansion vector includes the orientation of an edge tangent flow vector from the input image or the ratio image, or alternatively, a direction normal to a boundary formed by a pixel taking a predetermined ratio in the ratio image.

6. The image processing apparatus according to claim 1 , wherein

if it is determined that the 3-value image updated by the updating means is identical or nearly identical to the 3-value image before being updated by the updating means, then

the ratio image generating means generates a ratio image from the 3-value image updated by the updating means and the input image, wherein the ratio image is made up of a fourth value that indicates, on a per-pixel basis, the ratio of the first value, and

the updating means sets all pixels to the third value within a predetermined range near a pixel in the 3-value image that corresponds to a pixel in the ratio image whose fourth value is greater than a minimum value and less than a maximum value.

7. The image processing apparatus according to claim 6 , wherein

until it is determined that the 3-value image updated by the updating means is identical or nearly identical to the 3-value image before being updated by the updating means,

the ratio image generating means and the updating means repeat the processing whereby

a ratio image is generated from the 3-value image updated by the updating means and the input image, wherein the ratio image is made up of a fourth value that indicates, on a per-pixel basis, the ratio of the first value, and

all pixels are set to the third value within a predetermined range near a pixel in the 3-value image that corresponds to a pixel in the ration image whose fourth value is greater than a minimum value and less than a maximum value.

8. An image processing method for an image processing apparatus, the image processing apparatus including

3-value image generating means for generating a 3-value image made up of first through third values from a 2-value image, wherein the 2-value image is made up of a first value indicating, on a per-pixel basis, a foreground image region in an input image, as well as a second value similarly indicating a background image region, and wherein the third value of the 3-value image indicates an unknown region defined differently from both the foreground image region and the background image region such that the unknown region is defined having a predetermined width at the boundary between the foreground image region and the background image region,

ratio image generating means for generating a ratio image from the input image and the 3-value image, wherein the ratio image is made up of a fourth value that indicates, on a per-pixel basis, the ratio of the first value,

updating means for updating the 3-value image by defining a predetermined range near a pixel in the 3-value image that corresponds to a pixel in the ratio image whose fourth value is greater than a minimum value and less than a maximum value, and setting all pixels within the defined range to the third value,

determining means for determining whether or not the 3-value image updated by the updating means is identical or nearly identical to the 3-value image before being updated by the updating means, and

output means for outputting the updated 3-value image if it is determined that the 3-value image updated by the updating means is identical or nearly identical to the 3-value image before being updated by the updating means, the image processing method comprising the steps of:

by means of the 3-value image generating means, generating a 3-value image made up of first through third values from a 2-value image, wherein the 2-value image is made up of a first value indicating, on a per-pixel basis, a foreground image region in an input image, as well as a second value similarly indicating a background image region, and wherein the third value of the 3-value image indicates an unknown region defined differently from both the foreground image region and the background image region such that the unknown region is defined having a predetermined width at the boundary between the foreground image region and the background image region;

by means of the ratio image generating means, generating a ratio image from the input image and the 3-value image, wherein the ratio image is made up of a fourth value that indicates, on a per-pixel basis, the ratio of the first value;

by means of the updating means, updating the 3-value image by defining a predetermined range near a pixel in the 3-value image that corresponds to a pixel in the ratio image whose fourth value is greater than a minimum value and less than a maximum value, and setting all pixels within the defined range to the third value;

by means of the determining means, determining whether or not the 3-value image updated by the updating means is identical or nearly identical to the 3-value image before being updated by the updating means; and

by means of the output means, outputting the updated 3-value image if it is determined that the 3-value image updated by the updating means is identical or nearly identical to the 3-value image before being updated by the updating means.

9. A non-transitory computer-readable storage medium encoded with instructions which, when executed on a processor, cause processing to be executed on a computer that controls an image processing apparatus, the image processing apparatus including

3-value image generating means for generating a 3-value image made up of first through third values from a 2-value image, wherein the 2-value image is made up of a first value indicating, on a per-pixel basis, a foreground image region in an input image, as well as a second value similarly indicating a background image region, and wherein the third value of the 3-value image indicates an unknown region defined differently from both the foreground image region and the background image region such that the unknown region is defined having a predetermined width at the boundary between the foreground image region and the background image region,

ratio image generating means for generating a ratio image from the input image and the 3-value image, wherein the ratio image is made up of a fourth value that indicates, on a per-pixel basis, the ratio of the first value,

updating means for updating the 3-value image by defining a predetermined range near a pixel in the 3-value image that corresponds to a pixel in the ratio image whose fourth value is greater than a minimum value and less than a maximum value, and setting all pixels within the defined range to the third value,

determining means for determining whether or not the 3-value image updated by the updating means is identical or nearly identical to the 3-value image before being updated by the updating means, and

output means for outputting the updated 3-value image if it is determined that the 3-value image updated by the updating means is identical or nearly identical to the 3-value image before being updated by the updating means, the processing of the program comprising the steps of:

by means of the 3-value image generating means, generating a 3-value image made up of first through third values from a 2-value image, wherein the 2-value image is made up of a first value indicating, on a per-pixel basis, a foreground image region in an input image, as well as a second value similarly indicating a background image region, and wherein the third value of the 3-value image indicates an unknown region defined differently from both the foreground image region and the background image region such that the unknown region is defined having a predetermined width at the boundary between the foreground image region and the background image region;

by means of the ratio image generating means, generating a ratio image from the input image and the 3-value image, wherein the ratio image is made up of a fourth value that indicates, on a per-pixel basis, the ratio of the first value;

by means of the updating means, updating the 3-value image by defining a predetermined range near a pixel in the 3-value image that corresponds to a pixel in the ratio image whose fourth value is greater than a minimum value and less than a maximum value, and setting all pixels within the defined range to the third value;

by means of the determining means, determining whether or not the 3-value image updated by the updating means is identical or nearly identical to the 3-value image before being updated by the updating means; and

by means of the output means, outputting the updated 3-value image if it is determined that the 3-value image updated by the updating means is identical or nearly identical to the 3-value image before being updated by the updating means.

10. An image processing apparatus, comprising:

a 3-value image generator configured to generate a 3-value image made up of first through third values from a 2-value image, wherein the 2-value image is made up of a first value indicating, on a per-pixel basis, a foreground image region in an input image, as well as a second value similarly indicating a background image region, and wherein the third value of the 3-value image indicates an unknown region defined differently from both the foreground image region and the background image region such that the unknown region is defined having a predetermined width at the boundary between the foreground image region and the background image region;

a ratio image generator configured to generate a ratio image from the input image and the 3-value image, wherein the ratio image is made up of a fourth value that indicates, on a per-pixel basis, the ratio of the first value;

an updater configured to update the 3-value image by defining a predetermined range near a pixel in the 3-value image that corresponds to a pixel in the ratio image whose fourth value is greater than a minimum value and less than a maximum value, and setting all pixels within the defined range to the third value;

a determining unit configured to determine whether or not the 3-value image updated by the updater is identical or nearly identical to the 3-value image before being updated by the updater; and

an output unit configured to output the updated 3-value image if it is determined that the 3-value image updated by the updater is identical or nearly identical to the 3-value image before being updated by the updater.

11. The image processing apparatus of claim 10 , further comprising:

an expansion amount unit configured to define, on a per-pixel basis, a range near a pixel in the 3-value image that corresponds to a pixel in the ratio image whose fourth value is greater than a minimum value and less than a maximum value, the range being defined in the form of an expansion amount;

wherein the updater is further configured to update the 3-value image by setting all pixels within a predetermined range to the third value, the predetermined range being that defined by the expansion amount near a pixel in the 3-value image that corresponds to a pixel in the ratio image whose fourth value is greater than a minimum value and less than a maximum value.

12. The image processing apparatus of claim 10 , further comprising:

an expansion direction unit configured to define, on a per-pixel basis, a range near a pixel in the 3-value image that corresponds to a pixel in the ratio image whose fourth value is greater than a minimum value and less than a maximum value, the range being defined in the form of an expansion direction;

wherein the updater if further configured to update the 3-value image by setting all pixels within a predetermined range to the third value, the predetermined range being that defined by the expansion direction near a pixel in the 3-value image that corresponds to a pixel in the ratio image whose fourth value is greater than a minimum value and less than a maximum value.

13. The image processing apparatus of claim 10 , further comprising:

an expansion vector defining unit configured to define, on a per-pixel basis, a range near a pixel in the 3-value image that corresponds to a pixel in the ratio image whose fourth value is greater than a minimum value and less than a maximum value, the range being defined in the form of an expansion vector made up of an expansion direction and an expansion amount;

wherein the updater is further configured to update the 3-value image by setting all pixels within a predetermined range to the third value, the predetermined range being that defined by the expansion vector near a pixel in the 3-value image that corresponds to a pixel in the ratio image whose fourth value is greater than a minimum value and less than a maximum value.

14. The image processing apparatus of claim 13 , wherein the expansion direction of the expansion vector includes the orientation of an edge tangent flow vector from the input image or the ratio image, or alternatively, a direction normal to a boundary formed by a pixel taking a predetermined ratio in the ratio image.

15. The image processing apparatus of claim 10 , wherein

if it is determined that the 3-value image updated by the updater is identical or nearly identical to the 3-value image before being updated by the updater, then

the ratio image generator generates a ratio image from the 3-value image updated by the updater and the input image, wherein the ratio image is made up of a fourth value that indicates, on a per-pixel basis, the ratio of the first value, and

the updater sets all pixels to the third value within a predetermined range near a pixel in the 3-value image that corresponds to a pixel in the ratio image whose fourth value is greater than a minimum value and less than a maximum value.

16. The image processing apparatus of claim 15 , wherein

until it is determined that the 3-value image updated by the updater is identical or nearly identical to the 3-value image before being updated by the updater,

the ratio image generator and the updater repeat the processing whereby

a ratio image is generated from the 3-value image updated by the updater and the input image, wherein the ratio image is made up of a fourth value that indicates, on a per-pixel basis, the ratio of the first value, and

all pixels are set to the third value within a predetermined range near a pixel in the 3-value image that corresponds to a pixel in the ration image whose fourth value is greater than a minimum value and less than a maximum value.

17. The image processing method of claim 8 , the image processing apparatus further including expansion amount defining means for defining, on a per-pixel basis, a range near a pixel in the 3-value image that corresponds to a pixel in the ratio image whose fourth value is greater than a minimum value and less than a maximum value, the range being defined in the form of an expansion amount, the method further comprising:

by means of the updating means, updating the 3-value image by setting all pixels within a predetermined range to the third value, the predetermined range being that defined by the expansion amount near a pixel in the 3-value image that corresponds to a pixel in the ratio image whose fourth value is greater than a minimum value and less than a maximum value.

18. The image processing method of claim 8 , the image processing apparatus further including expansion direction defining means for defining, on a per-pixel basis, a range near a pixel in the 3-value image that corresponds to a pixel in the ratio image whose fourth value is greater than a minimum value and less than a maximum value, the range being defined in the form of an expansion direction, the method further comprising:

by means of the updating means, updating the 3-value image by setting all pixels within a predetermined range to the third value, the predetermined range being that defined by the expansion direction near a pixel in the 3-value image that corresponds to a pixel in the ratio image whose fourth value is greater than a minimum value and less than a maximum value.

19. The image processing method of claim 1 , the image process apparatus further including expansion vector defining means for defining, on a per-pixel basis, a range near a pixel in the 3-value image that corresponds to a pixel in the ratio image whose fourth value is greater than a minimum value and less than a maximum value, the range being defined in the form of an expansion vector made up of an expansion direction and an expansion amount, the method further comprising:

by the updating means, updating the 3-value image by setting all pixels within a predetermined range to the third value, the predetermined range being that defined by the expansion vector near a pixel in the 3-value image that corresponds to a pixel in the ratio image whose fourth value is greater than a minimum value and less than a maximum value.

20. The image processing method of claim 19 , wherein the expansion direction of the expansion vector includes the orientation of an edge tangent flow vector from the input image or the ratio image, or alternatively, a direction normal to a boundary formed by a pixel taking a predetermined ratio in the ratio image.