Two-dimensional code reading method, two-dimensional code reading program, recording medium with two-dimensional code reading program, two-dimentional code reading device, digital camera and portable terminal with digital camera

• US 20040011872A1
• Filed: 07/17/2003
• Published: 01/22/2004
• Est. Priority Date: 07/18/2002
• Status: Active Grant

• Current Assignee: Sharp Kabushiki Kaisha (Hon Hai Precision Industry Co., Ltd.)
• Original Assignee: Sharp Kabushiki Kaisha (Hon Hai Precision Industry Co., Ltd.)
• Inventors: Shimizu, Hajime
• Granted Patent: US 6,786,412 B2
• Time in Patent Office: Days
• US Class Current: 235/462.11
• CPC Class Codes: G06K 7/14 using light without selection of wavelength, e.g. sensing reflected white light G06K7/10831 - G06K7/1097 take precedence
• CPC Class Codes: G06K 7/1443 locating of the code in an image
• CPC Class Codes: G06K 7/1456 determining the orientation of the optical code with respect to the reader and correcting therefore
• CPC Class Codes: H04N 2101/00 Still video cameras

Abstract

Coordinate positions of four points including three position detecting element patterns and an indexing pattern are detected from a two-dimensional code image captured, the two-dimensional code size is determined, coefficients of equations for determining coordinate positions corresponding to center positions of respective cells compensated for inclination of the image by adding depth information are determined, the coordinate positions of respective cell center positions are determined according to the calculation equations by applying the determined coefficients, brightness/darkness is discriminated from image data corresponding to the respective cell center positions and binary data (0 or 1) for respective cells are generated, information of the two-dimensional code is reproduced based on the binary data. The equations are expressed by recurrence formulas. The coefficients determined from the coordinate positions of 4 points of the two-dimensional code are divided by the same constant to make them integers.

Claims

1. A two-dimensional code reading method comprising processing steps of acquiring an image of a matrix type two-dimensional code composed of a number of cells arranged in vertical and horizontal directions to form a matrix of the cells each representing binary coded data, deciding a two-dimensional code area in the image, setting inspection lines identifying a center position of each of the cells, said inspection lines each joining two paired opposites of four sides defining the boundary of the decided two-dimensional code area and reproducing information of the two-dimensional code based on the inspection lines set by the inspection line setting processing, wherein coefficients in image position calculating equations for calculating coordinate positions of center positions of respective cells in the two-dimensional code compensated for image inclination by adding inclination information for the two-dimensional code are calculated for setting the inspection lines on the two-dimensional code image based on coordinate positions of 4 points within the two-dimensional code area decided by the two-dimensional code area deciding step.

2. A two-dimensional code reading method as defined in claim 1, wherein each of the image position calculating equations for determining the coordinate positions of the center positions of the respective cells in the two-dimensional code image is expressed by a recurrence formula with respect to a center position of each of the cells to reduce a volume of calculation for determining the coordinate positions of the center positions of respective cells compensated for image inclination by adding the inclination information of the two-dimensional code.

3. A two-dimensional code reading method as defined in claim 1 or 2, wherein coefficients in the image position calculating equations for calculating coordinate positions at four corners of the two-dimensional code area are divided by a predetermined same constant to make them integers and the coordinate positions of the cell center positions are determined by calculation with the integers only.

4. A two-dimensional code reading method as defined in claim 1 or 2, wherein a constant for dividing the coefficients symbolically determined for the image position calculating equations and selected from constants frequently and commonly used in the image position calculating equations is used to divide and convert the coefficients to smaller in size coefficients to make the two-dimensional code readable.

6. A two-dimensional code reading program which describes the two-dimensional code reading method defined in any one of claims 1 to 5 by program codes executable by a computer.

7. A program recording medium which is readable by a computer and holding thereon the two-dimensional code reading program of claim 6.

5. A two-dimensional code reading method comprising processing steps of acquiring an image of a stack type two-dimensional code composed of a number of bar codes arranged in multiple layers in a direction perpendicular to a direction of arrangement of bars in each bar code representing data, deciding a two-dimensional code area in the image;

setting an inspection line identifying a center position of each of the bar codes, said inspection line joining one of two pairs of opposites of four sides representing the boundary of the decided two-dimensional code area, said pair opposite to each other in the direction of arrangement of bars in each bar code; and

reproducing information of the two-dimensional code based on the inspection lines set in the inspection line setting step, wherein coefficients in image position calculating equations for calculating coordinate positions of center positions of respective cells in the two-dimensional code compensated for image inclination by adding inclination information for the two-dimensional code are calculated for setting the inspection lines on the two-dimensional code image based on coordinate positions of 4 points within the two-dimensional code area decided by the two-dimensional code area deciding step.

8. A two-dimensional code reading device comprising an image capturing portion for capturing an image of a matrix type two-dimensional code composed of a number of cells arranged in vertical and horizontal directions to form a matrix of the cells each representing binary coded data, a two-dimensional code area deciding portion for deciding a two-dimensional code area in the two-dimensional code image, an inspection line setting portion for setting inspection lines identifying a center position of each of the cells, said inspection lines each joining two paired opposites of four sides defining the boundary of the decided two-dimensional code area and a decoding portion for reproducing information of the two-dimensional code based on the inspection lines, wherein the inspection line setting portion based on coordinate positions of 4 points within the two-dimensional code area decided by the two-dimensional code area deciding portion calculates coefficients for image position calculating equations for determining coordinate positions of center positions of respective cells in the two-dimensional code compensated for the inclination of the image by adding inclination information for the two-dimensional code.

9. A two-dimensional code reading device as defined in claim 8, wherein each of the image position calculating equations for determining the coordinate positions of the center positions of the respective cells in the two-dimensional code image is expressed by a recurrence formula with respect to a center position of each of the cells to reduce a volume of calculations for determining the coordinate positions of the center positions of respective cells compensated for image inclination by adding the inclination of the two-dimensional code by adding inclination information for the two-dimensional code.

10. A two-dimensional code reading device as defined in claim 8 or 9, wherein coefficients in the image position calculating equations for calculating coordinate positions at four corners of the two-dimensional code area are divided by a predetermined same constant to make them integers and the coordinate positions of the cell center positions are determined by calculation with the integers only.

11. A two-dimensional code reading device as defined in claim 8 or 9, wherein a constant for dividing the coefficients symbolically determined for the image position calculating equations and selected from constants frequently and commonly used in the image position calculating equations is used to divide and convert the coefficients to smaller in size coefficients to make the two-dimensional code readable.

12. A digital camera incorporating a two-dimensional code reading device as defined in any one of claims 8 to 11.

13. A portable telephone with a digital camera, which incorporates a two-dimensional code reading device as defined in any one of claims 8 to 11.