Apparatus to detect homogeneous region of image using adaptive threshold

• US 20060147113A1
• Filed: 09/29/2005
• Published: 07/06/2006
• Est. Priority Date: 12/28/2004
• Status: Active Grant

• Current Assignee: Samsung Electronics Co. Ltd.
• Original Assignee: Samsung Electronics Co. Ltd.
• Inventors: Han, Seung-hoon
• Granted Patent: US 7,970,208 B2
• Time in Patent Office: Days
• US Class Current: 382/171
• CPC Class Codes: G06T 2207/20008 Globally adaptive
• CPC Class Codes: G06T 7/11 Region-based segmentation
• CPC Class Codes: G06V 10/507 Summing image-intensity values; Histogram projection analysis

Abstract

A homogeneous region detector of an image using an adaptive threshold, and a method of the same. The homogeneous region detector includes a global region standard deviation calculation part to calculate a global region standard deviation of a whole region of an input image, a local region standard deviation calculation part to divide the input image into a predetermined number of local regions and to calculate a local region standard deviation of the each local region, and a homogeneous region determination part to separate the homogeneous region from a feature region in the input image using an adaptive threshold calculated based on entropy of the input image. Accordingly, the homogeneous region can be precisely detected by effectively separating the homogeneous region from the feature region of the input image by using the threshold adaptively calculated based on the entropy of the input image, so that the homogeneous region can be applied to various fields of image processing.

Claims

1. A homogeneous region detector using an adaptive threshold, the homogenous region detector comprising:

a global region standard deviation calculation part to calculate a global region standard deviation of a whole region of an input image;

a local region standard deviation calculation part to divide the input image into a predetermined number of local regions and to calculate a local region standard deviation of each local region; and

a homogeneous region determination part to separate the homogeneous region from a feature region in the input image using an adaptive threshold calculated based on entropy of the input image.

2. The homogeneous region detector of claim 1, wherein the homogeneous region determination part comprises:

an adaptive threshold calculation part to calculate the adaptive threshold based on the global region standard deviation and an entropy constant of the input image; and

a comparison part to compare the calculated adaptive threshold with the local region standard deviation of each local region and to determine one of the local regions to be the homogeneous region when the adaptive threshold is greater than the respective local region standard deviation.

3. The homogeneous region detector of claim 1, wherein the adaptive threshold is calculated by the following expression:

4. The homogeneous region detector of claim 3, wherein the entropy constant K comprises a bit/symbol measurement of the input image.

5. A homogeneous region detector to detect a homogeneous region of an input image, the homogenous region detector comprising:

a calculation unit to calculate a global standard deviation of the input image, to calculate a plurality of local standard deviations corresponding to a plurality of local regions of the input image, and to calculate an adaptive threshold based on the calculated global standard deviation and an entropy constant of the input image; and

a comparison unit to compare the plurality of local standard deviations to the adaptive threshold calculated by the calculation unit to determine whether the corresponding plurality of local regions of the input image are homogeneous.

6. The homogenous region detector of claim 5, wherein the comparison unit determines one of the plurality of local regions to be homogenous when the corresponding one of the plurality of local standard deviations is less than the adaptive threshold.

7. The homogenous region detector of claim 5, wherein the calculation unit calculates a maximum local standard deviation of a homogenous region of the image based on the global standard deviation and the entropy constant and sets the adaptive threshold to be equal to the maximum local standard deviation of the homogenous region.

8. The homogenous region detector of claim 5, wherein the entropy constant comprise a measure of information per symbol in the input image.

9. A homogenous region detector to detect a homogenous region of an input image, the homogenous region detector comprising:

an adaptive threshold calculation unit to calculate an adaptive threshold according to a predetermined property of the input image;

a standard deviation calculation unit to divide the input image into a plurality of regions and to calculate a local standard deviation of each region; and

a comparison unit to compare the local standard deviation of each region to the adaptive threshold calculated by the adaptive threshold calculation part to determine a homogenous region of the input image.

10. The homogeneous region detector of claim 9, wherein the predetermined property of the input image comprises entropy of the input image.

11. The homogenous region detector of claim 10, wherein the standard deviation calculation unit calculates a global standard deviation of the input image, and the adaptive threshold calculation part calculates the adaptive threshold based on an entropy constant of the input image and the global standard deviation of the input image calculated by the calculation unit.

12. The homogenous region detector of claim 9, wherein the comparison unit determines one of the regions of the image to be the homogenous region when the local standard deviation of the one of the regions is less than the adaptive threshold value.

13. A method of detecting a homogeneous region of an image using an adaptive threshold, the method comprising:

calculating a global region standard deviation of a whole region of an input image, dividing the input image into a certain number of local regions, and calculating a local region standard deviation of each local region; and

separating a homogeneous region from a feature region in the input image using an adaptive threshold calculated based on entropy of the input image.

14. The method of claim 13, wherein the separating of the homogenous region from the feature region in the image comprises:

calculating the adaptive threshold based on the global region standard deviation and an entropy constant of the input image; and

comparing the calculated adaptive threshold with the local region standard deviation σ

_m of each local region and determining one of the local regions to be the homogeneous region when the adaptive threshold is greater than the respective local region standard deviation.

15. The method of claim 13, wherein the adaptive threshold is calculated by the following expression:

16. The method of claim 15, wherein the entropy constant comprises a bit/symbol measurement of the input image.

17. A method of detecting a homogenous region of an input image, the method comprising:

calculating an adaptive threshold according to a predetermined property of the input image;

calculating a plurality of local standard deviations corresponding to a plurality of regions of the input image; and

comparing the plurality of local standard deviations to the calculated adaptive threshold to determine a homogenous region of the input image.

18. The method of claim 17, wherein the predetermined property of the input image comprises entropy of the input image.

19. The method of claim 18, wherein the calculating of the adaptive threshold comprises:

calculating a global standard deviation of the input image; and

calculating the adaptive threshold based on the calculated global standard deviation and an entropy constant of the input image.

20. The method of claim 17, wherein the comparing of the plurality of local standard deviations comprises:

determining that one of the plurality of regions of the input image is the homogenous region when the corresponding one of the plurality of local standard deviations is less than the adaptive threshold.

21. A computer readable recording medium comprising executable codes to perform a method of detecting a homogenous region of an image, the method comprising:

calculating a global region standard deviation of a whole region of an input image, dividing the input image into a certain number of local regions, and calculating a local region standard deviation of each local region; and

separating a homogeneous region from a feature region in the input image using an adaptive threshold calculated based on entropy of the input image.

22. A computer readable recording medium comprising executable codes to perform a method of detecting a homogenous region of an input image, the method comprising:

calculating an adaptive threshold according to a predetermined property of the input image;

calculating a plurality of local standard deviations corresponding to a plurality of regions of the input image; and

comparing the plurality of local standard deviations to the calculated adaptive threshold to determine a homogenous region of the input image.