Method of detecting and reading postal bar codes

• US 4,822,986 A
• Filed: 04/17/1987
• Issued: 04/18/1989
• Est. Priority Date: 04/17/1987
• Status: Expired due to Term

• Current Assignee: Bowe Bell & Howell Company
• Original Assignee: Recognition Equipment Incorporated
• Inventors: Habitzreiter, Richard K., Guthmueller, Rodney K.
• Primary Examiner(s): TRAFTON, DAVID
• Application Number:
  US07/040,267
• Time in Patent Office: 732 Days
• Field of Search: 235/455, 235/456, 235/462, 235/470
• US Class Current: 235/462.02
• CPC Class Codes: B07C 3/14 using light-responsive detecting means for information carriers G06K7/14
• CPC Class Codes: G06K 7/1092 sensing by means of TV-scanning

Abstract

A Bar Code Reader of a Video Processor Unit receives video data from a scanner and processes it to locate a bar code at the bottom of a document which represents a postal zip code. The scanner generates an array of cells of video data and provides each cell with a gray weight value corresponding to a detected blackness level of a small portion of the scanned document. The Bar Code Reader moves a template mask over the array and calculates area sums of gray weight values for cells within predetermined areas of the template mask. The area sums are used to compute Bar scores for determining the presence and position of tall and short bars in a bar code field. The positions of the tall and short bars in the bar code field are translated into postal zip code information.

Claims

1. A method of reading a bar code containing tall and short bars on a document, comprising the steps of:

detecting blackness levels of markings on the document;

generating cells of video data, each cell having a gray weight value corresponding to the detected blackness level of a small area of the document; and

analyzing the gray weight values to determine the positions of tall and short bars in the bar code.

2. The method of claim 1, wherein the step of detecting blackness levels comprises scanning the document to generate the cells of video data.

3. The method of claim 2, further comprising the step of forming an array of the cells comprising vertical scans and horizontal rows.

4. The method of claim 3, further comprising:

moving a template mask over the array of cells;

calculating area sums of the gray weight values within predetermined areas of the template mask; and

computing bar scores from the area sums.

5. The method of claim 4, wherein the step of analyzing the gray weight values further comprises:

comparing the bar scores to determine the positions of bar code elements;

linking the bar code elements based on predetermined criteria to produce a bar code field; and

translating the position of the tall and short bars in the bar code field into electronic data.

6. A method of detecting and reading a postal bar code containing tall and short bars on a document, comprising the steps of:

scanning the document;

detecting blackness levels of markings on the scanned document;

generating an array of cells of video data, each cell having a gray weight value corresponding to the detected blackness level of a small portion of the scanned document;

determining area sums of the gray weight values for a plurality of cells in the array;

calculating bar scores from the area sums;

analyzing the bar scores to determine the presence and position of tall and short bars in the bar code; and

translating the position of the tall and short bars into postal zip code information.

7. The method of claim 6, wherein the step of determining area sums comprises:

moving a template mask over the array; and

calculating the area sums for the cells within predetermined areas of the template mask.

8. The method of claim 6, wherein the step of analyzing the bar scores comprises:

comparing the bar scores to determine the presence and position of bar code elements; and

linking the bar code elements based on predetermined criteria to produce a bar code field comprising the tall and short bars.

9. A method of detecting and decoding a postal bar code containing tall and short bars on a document, comprising the steps of:

scanning the document;

detecting blackness levels of markings on the scanned document;

generating an array of cells of video data, each cell having a gray weight value corresponding to the detected blackness level of a small portion of the scanned document;

moving a template mask over the array;

calculating area sums of gray weight values of the video cells within predetermined areas of the template mask;

computing bar scores from the area sums;

comparing the bar scores to determine the presence and position of bar code elements;

linking the bar code elements based on predetermined criteria to produce a bar code field comprising tall and short bars; and

translating the positions of the tall and short bars in the bar code field into postal zip code information.

10. The method of claim 9, wherein the step of calculating area sums comprises:

calculating a window area sum of cells within a window of the template mask;

calculating a tall bar area sum of cells within a tall bar area inside the window; and

calculating a short bar area sum of cells within a short bar area inside the tall bar area.