Detecting bar code candidates

• US 20010006191A1
• Filed: 02/26/2001
• Published: 07/05/2001
• Est. Priority Date: 06/03/1996
• Status: Active Grant

• Current Assignee: Datalogic Automation Incorporated (Datalogic S.p.A.)
• Original Assignee: Accu-Sort Systems Incorporated (Datalogic S.p.A.)
• Inventors: Shreesha, Vasanth, Neskovic, Milorad, Hecht, Kurt, Cohen, Edward
• Granted Patent: US 6,386,454 B2
• Time in Patent Office: Days
• US Class Current: 235/462.16
• 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

Abstract

An area of interest is scanned to produce pixels of the scanned area. The pixels are divided into a plurality of blocks. For each block, an orientation of a spanning line or a lack of orientation is determined. Contiguous ones of the blocks are clustered, when their orientation is within a certain tolerance level. Each cluster has a length and a width. The length is longer than the width. If the orientation of a cluster'"'"'s block is perpendicular to the length of that cluster, that cluster is selected as a bar code candidate.

Claims

1. A method for detecting bar code candidates, the method comprising:

scanning an area of interest to produce pixels of the scanned area;

dividing the pixels into a plurality of blocks;

for each block, determining an orientation of a spanning line or a lack of orientation when a spanning line is not present;

clustering contiguous ones of the blocks having their orientation within a certain tolerance level, each cluster having a length and a width, the length longer than the width; and

selecting candidate bar codes from the clusters, by determining if the orientation of each cluster'"'"'s blocks is perpendicular to the length of the cluster.

2. The method of

claim 1

wherein the bar code is a 1D bar code.

3. The method of

claim 1

further comprising binarizing the pixels prior to the dividing.

4. The method of

claim 1

wherein the plurality of blocks are a plurality of grid blocks.

5. The method of

claim 4

wherein the grid blocks have a square shape.

6. The method of

claim 3

wherein the step of for each block, determining an orientation of a spanning line or a lack of orientation comprises:

detecting a transition within that block;

tracing a transition edge using the detected transition;

determining a spanning line when the transition edge reaches two different edges of that block; and

determining an orientation for that block using a slope of the spanning line and a lack of orientation when a spanning line is not present in that block.

7. The method of

claim 6

wherein the determining slope of the spanning line is based on a slope of two points of intersection of the spanning line with the two different edges.

8. The method of

claim 6

further comprising discarding a spanning line having a pixel length exceeding a threshold pixel length prior to the orientation determining.

9. A bar code scanner comprising:

a scanner for scanning an area of interest to produce pixels of the scanned area;

a processor for executing instructions including;

scanning an area of interest to produce pixels of the scanned area;

dividing the pixels into a plurality of blocks;

for each block, determining an orientation of a spanning line or a lack of orientation when a spanning line is not present;

clustering contiguous ones of the blocks having their orientation within a certain tolerance level, each cluster having a length and a width, the length longer than the width; and

selecting candidate bar codes from the clusters, by determining if the orientation of each cluster'"'"'s blocks is perpendicular to the length of the cluster.

10. The bar code scanner of

claim 9

wherein the scanner is a photo-sensitive detector.

11. The bar code scanner of

claim 9

wherein the scanner is a charge coupled device (CCD).

12. The bar code scanner of

claim 11

wherein the CCD has a one dimensional array.

13. The bar code scanner of

claim 9

wherein the bar code is a 1D bar code.

14. The bar code scanner of

claim 9

wherein the processor further executes instructions for binarizing the pixels prior to the dividing.

15. The bar code scanner of

claim 14

wherein the plurality of blocks are a plurality of grid blocks.

16. The bar code scanner of

claim 15

wherein the grid blocks have a square shape.

17. The bar code scanner of

claim 14

wherein the step of for each block, determining an orientation of a spanning line or a lack of an orientation comprises:

detecting a transition within that block;

tracing a transition edge using the detected transition;

determining a spanning line when the transition edge reaches two different edges of that block; and

determining an orientation for that block using a slope of the spanning line and a lack of orientation when a spanning line is not present in that block.

18. The bar code scanner of

claim 17

wherein the determining slope of the spanning line is based on a slope of two points of intersection of the spanning line with the two different edges.

19. The bar code scanner of

claim 17

the processor executing instructions for discarding a spanning line have a pixel length exceeding a threshold pixel length prior to the orientation determining.