Apparatus and method for image processing to label an object in a binary image

• US 7,321,687 B2
• Filed: 02/28/2003
• Issued: 01/22/2008
• Est. Priority Date: 03/07/2002
• Status: Expired due to Fees

• Current Assignee: Canon Kabushiki Kaisha (Canon Inc.)
• Original Assignee: Canon Kabushiki Kaisha (Canon Inc.)
• Inventors: Yamamoto, Kunihiro
• Primary Examiner(s): Chen; Wenpeng
• Assistant Examiner(s): Ge; Yuzhen
• Application Number:
  US10/375,195
• Publication Number:
  US 20030169921A1
• Time in Patent Office: 1,789 Days
• Field of Search: 382/174, 382/170
• US Class Current: 382/170
• CPC Class Codes: G06V 30/1478 of characters or characters lines
• CPC Class Codes: H04N 1/3878 Skew detection or correction

Abstract

This disclosure relates to an image processing apparatus or an image processing method, and takes as its technical problem the fact that conventionally it is difficult to perform a process of carving out a rectangle with high precision in a noisy environment.

Therefore, as to an image made by binarizing an original image, histograms of the numbers of horizontal and vertical black pixels thereof are created and trapezoidal approximation is performed on the histograms so as to detect vertex coordinates indicating an extent of a rectangular area in the binary image. An inclination direction of the rectangular area in the extent is detected so that the rectangular area can be detected from the binary image with high precision.

Claims

1. An image processing method for labeling an object in a binary image, comprising:

a black block detection step of, in said binary image, detecting as a black block a block of a predetermined size having a number of black pixels therein equal to or higher than a predetermined ratio; and

a label replacement step of replacing a pixel connection area with a predetermined label value, wherein the pixel connection area is started from the black block detected in said black block detection step;

wherein said label replacement step includes a step of starting the replacement at the detected black block when the black block is detected in said black block detection step, and wherein, in a case in which said black blocks of the predetermined size are not discovered in said binary image, said black block detection step detects the black block of a smaller size than the predetermined size.

2. The image processing method according to claim 1, wherein said black block detection step detects as said black block the block of which the inside is composed entirely of black pixels.

3. The image processing method according to claim 1, wherein said black block detection step comprises:

a division step of dividing said entire binary image into said blocks of the predetermined size; and

a determination step of determining whether or not each of said blocks is the black block.

4. The image processing method according to claim 1, wherein said black block detection step detects the black block by sequentially deviating the positions of said blocks of the predetermined size in said binary image.

5. The image processing method according to claim 1, wherein said black block is a rectangle.

6. The image processing method according to claim 1, wherein said black block is a polygon.

7. An image processing method for labeling an object in a binary image, comprising:

a black block detection step of, in said binary image, detecting as a black block a block of a predetermined size having a number of black pixels therein equal to or higher than a predetermined ratio; and

a label replacement step of replacing a pixel connection area with a predetermined label value, wherein the pixel connection area is started from the black block detected in said black block detection step;

wherein said label replacement step includes;

a step of starting the replacement at the detected black block when the black block is detected in said black block detection step;

a reference label replacement step of replacing a reference line inside said black block with said label value;

an upper part label replacement step of replacing the black pixels connected to a portion more upward than said reference line with said label value; and

a lower part label replacement step of replacing the black pixels connected to a portion more downward than said reference line with said label value.

8. An image processing method for labeling an object in a binary image, comprising:

a black block detection step of, in said binary image, detecting as a black block a block of a predetermined size having a number of black pixels therein equal to or higher than a predetermined ratio; and

a label replacement step of replacing a pixel connection area with a predetermined label value, wherein the pixel connection area is started from the black block detected in said black block detection step;

wherein said label replacement step includes a step of starting the replacement at the detected black block when the black block is detected in said black block detection step, and wherein said black block is a circle.

9. An image processing apparatus for labeling an object in a binary image, comprising:

a black block detection component for, in said binary image, detecting as a black block a block of a predetermined size having a number of black pixels therein equal to or higher than a predetermined ratio; and

a label replacement component for a replacing pixel connection area with a predetermined label value, wherein the pixel connection area is started from the black block detected by said black block detection component;

wherein said label replacement component starts the replacement at the detected black block when the black block is detected by said black block detection component, and wherein, in a case in which said black blocks of the predetermined size are not discovered in said binary image, said black block detection component detects the black block of a smaller size than the predetermined size.

10. A computer readable medium, storing a program for implementing an image processing method executable on a computer, said program comprising:

a black block detection component for, in said binary image, detecting as a black block a block of a predetermined size having a number of black pixels therein equal to or higher than a predetermined ratio; and

a label replacement component for replacing a pixel connection area with a predetermined label value, wherein the pixel connection area is started from the black block detected by said black block detection component;

wherein said label replacement component starts the replacement at the detected black block when the black block is detected in by said black block detection component, and wherein, in a case in which said black blocks of the predetermined size are not discovered in said binary image, said black block detection component detects the black block of a smaller size than the predetermined size.

11. An image processing apparatus for labeling an object in a binary image, comprising:

a black block detection component that detects as a black block in said binary image, a block of a predetermined size having a number of black pixels therein equal to or higher than a predetermined ratio; and

a label replacement component of replacing a pixel connection area with a predetermined label value, in which the pixel connection area is started from the black block detected by said black block detection component;

wherein said label replacement component includes;

a component that starts the replacement at the detected black block when the black block is detected in said black block detection component;

a reference label replacement component that replaces a reference line inside said black block with said label value;

an upper part label replacement component that replaces the black pixels connected to a portion more upward than said reference line with said label value; and

a lower part label replacement component that replaces the black pixels connected to a portion more downward than said reference line with said label value.

12. A computer readable medium, storing a program for implementing an image processing method executable on a computer, said program comprising:

a black block detection component that detects as a black block in said binary image, a block of a predetermined size having a number of black pixels therein equal to or higher than a predetermined ratio; and

a label replacement component of replacing a pixel connection area with a predetermined label value, in which the pixel connection area is started from the black block detected by said black block detection component;

wherein said label replacement component includes;

a component that starts the replacement at the detected black block when the black block is detected in said black block detection component;

a reference label replacement component that replaces a reference line inside said black block with said label value;

an upper part label replacement component that replaces the black pixels connected to a portion more upward than said reference line with said label value; and

a lower part label replacement component that replaces the black pixels connected to a portion more downward than said reference line with said label value.

13. An image processing apparatus for labeling an object in a binary image, comprising:

a black block detection component that detects as a black block in said binary image, a block of a predetermined size having a number of black pixels therein equal to or higher than a predetermined ratio; and

a label replacement component that replaces pixel connection area with a predetermined label value, the pixel connection area is started from the black block detected by said black block detection component;

wherein said label replacement component includes a component that starts the replacement at the detected black block when the black block is detected by said black block detection component, and said black block is a circle.

14. A computer readable medium, storing a program for implementing an image processing method executable on a computer, said program comprising:

a black block detection component that detects as a black block in said binary image, a block of a predetermined size having a number of black pixels therein equal to or higher than a predetermined ratio; and

a label replacement component that replaces a pixel connection area with a predetermined label value, the pixel connection area is started from the black block detected by said black block detection component;

wherein said label replacement component includes a component that starts the replacement at the detected black block when the black block is detected by said black block detection component, and said black block is a circle.