Apparatus, method for extracting boundary of object in image, and electronic device thereof

Patent metadata

Field	Value
Publication number	US-9292931-B2
Application number	US-201313912805-A
Country	US
Kind code	B2
Filing date	Jun 7, 2013
Priority date	Jun 7, 2012
Publication date	Mar 22, 2016
Grant date	Mar 22, 2016

Abstract

The invention provides an apparatus and method for extracting a boundary of an object in an image and an electronic device. The apparatus includes: a position determining unit, configured to determine a start point and an end point of a boundary of an object in an image and to determine a position of a reference point relevant to the start point and the end point; a first direction determining unit, configured to determine a first direction of the boundary; a gradient map obtaining unit, configured to obtain a gradient map of a first region; a gradient attenuating unit, configured to attenuate in the gradient map the gradients of a second region; and an extracting unit, configured to extract a boundary of an object. The technology of the invention can improve the accuracy of boundary extracting, and can be applied in the field of image processing.

First claim

The invention claimed is:

1. An apparatus for extracting a boundary of an object in an image, comprising:
memory;
a processor coupled to the memory and configured to:
determine a start point and an end point of the boundary of the object in the image and to determine a position of a reference point relevant to the start point and the end point;
determine a first direction of the boundary;
determine a second direction intersecting the first direction;
determine in the image a first region comprising the start point, the end point and the reference point and to obtain a gradient map of the first region;
determine at least one second region on at least one of two sides of the reference point along the second direction and to attenuate in the gradient map the gradients of the second region; and
extract a boundary between the start point and the end point based on the attenuated gradient map to obtain the boundary of the object.

2. The apparatus for extracting a boundary of an object in an image according to claim 1 , wherein the object is a document.

3. The apparatus for extracting a boundary of an object in an image according to claim 1 , wherein the processor is further configured:
to obtain a slope direction of a connecting line between the start point and the end point; and
to determine the slope direction of the connecting line as the first direction of the boundary.

4. The apparatus for extracting a boundary of an object in an image according to claim 1 , wherein the second direction is perpendicular to the first direction of the boundary.

5. The apparatus for extracting a boundary of an object in an image according to claim 1 , wherein the second region comprises one of or a superposition of at least two of a triangular region, a sector region, a banded region and a parabolic region.

6. The apparatus for extracting a boundary of an object in an image according to claim 1 , wherein a shape and/or a position of the second region is adjusted in response to an instruction input by a user.

7. The apparatus for extracting a boundary of an object in an image according to claim 1 , wherein the second region is located outside of a neighboring region of the reference point which has a predetermined size.

8. The apparatus for extracting a boundary of an object in an image according to claim 7 , wherein the neighboring region of the reference point which has a predetermined size is the following region:
a banded region with a predetermined size which comprises the reference point therein, with the length of the banded region extending along the first direction of the boundary; or
a circular region with a centre at the reference point.

9. The apparatus for extracting a boundary of an object in an image according to claim 1 , wherein
the gradient values of the second region in the attenuated gradient map are greater than the gradient values of the second region in the non-attenuated gradient map in a case where the gradient map is a color-inverted gradient map; and
the gradient values of the second region in the attenuated gradient map are less than the gradient values of the second region in the non-attenuated gradient map in a case where the gradient map is a gradient map without being color-inverted.

10. The apparatus for extracting a boundary of an object in an image according to claim 1 , wherein the processor is further configured to:
set the gradient value of the reference point to a value below a first predetermined threshold in a case where the gradient map is a color-inverted gradient map, and to set the gradient value of the reference point to a value above a second predetermined threshold in a case where the gradient map is a gradient map without being color-inverted; and
extract a boundary between the start point and the end point using a boundary tracking method and to determine the extracted boundary as the boundary of the object.

11. The apparatus for extracting a boundary of an object in an image according to claim 10 , wherein the processor is further configured as follows:
in a case where there are two reference points in the reference points the distance between which is within a predetermined distance range,
if the gradient map is a color-inverted gradient map, the gradients of the two reference points, the distance between which is within the predetermined distance range, are set to values within a third predetermined neighboring region range of 0; and
if the gradient map is a gradient map without being color-inverted, the gradients of the two reference points, the distance between which is within the predetermined distance range, are set to values within a fourth predetermined neighboring region range of 255.

12. The apparatus for extracting a boundary of an object in an image according to claim 1 , wherein the processor is further configured to:
fit the boundary of the object obtained.

13. The apparatus for extracting a boundary of an object in an image according to claim 12 , wherein the processor is further configured to set a weight of the reference point to be greater than a third predetermined threshold during a fitting process for the boundary of the object obtained.

14. An electronic device, comprising the apparatus for extracting a boundary of an object in an image according to claim 1 .

15. The electronic device according to claim 14 , wherein the electronic device is any one of a scanner, a camera, a computer, a mobile phone, a panel computer and a PAD (Personal Digital Assistant).

16. A method for extracting a boundary of an object in an image, comprising:
determining a start point and an end point of the boundary of the object in the image and determining a position of a reference point relevant to the start point and the end point;
determining a first direction of the boundary;
determining a second direction intersecting the first direction;
determining in the image a first region comprising the start point, the end point and the reference point, and obtaining a gradient map of the first region;
determining at least one second region on at least one of two sides of the reference point along the second direction;
attenuating in the gradient map the gradients of the second region and extracting a boundary between the start point and the end point based on the attenuated gradient map to obtain the boundary of the object.

17. The method for extracting a boundary of an object in an image according to claim 16 , wherein the object is a document.

18. The method for extracting a boundary of an object in an image according to claim 16 , wherein the step of determining the first direction of the boundary comprises:
obtaining a slope direction of a connecting line between the start point and the end point; and
determining the slope direction of the connecting line as the first direction of the boundary.

19. The method for extracting a boundary of an object in an image according to claim 16 , wherein the second direction is perpendicular to the first direction of the boundary.

20. A non-transitory computer readable storage medium on which a computer program that can be executed by a computing device is stored, wherein execution of the computer program enables the computing device to perform the method for extracting a boundary of an object in an image according to claim 16 .

Assignees

• Fujitsu Ltd

Inventors

• Pan Pan
• He Yuan
• Sun Jun
• Naoi Satoshi

Classifications

• G06T7/0083

  Physics · mapped topic

• G06T7/0085 Primary

  Physics · mapped topic

• G06T7/12 Primary

  Edge-based segmentation · CPC title