Bar code location and recognition processing system

• US 5,073,954 A
• Filed: 02/28/1989
• Issued: 12/17/1991
• Est. Priority Date: 02/28/1989
• Status: Expired due to Term

• Current Assignee: Siemens Dematic Corp. (Siemens AG)
• Original Assignee: ElectroCom Automation, Inc. (Mercedes-Benz Group AG)
• Inventors: Neff, Marion W., Mondie, George R., Van Tyne, Richard G.
• Primary Examiner(s): Boudreau, Leo H.
• Application Number:
  US07/317,293
• Time in Patent Office: 1,022 Days
• Field of Search: 235/436, 235/437, 235/462, 235/463, 235/494, 382/1, 382/18, 382/51
• US Class Current: 235/462.08
• CPC Class Codes: G06K 7/1092 sensing by means of TV-scanning
• CPC Class Codes: G06K 7/1093 sensing, after transfer of the image of the data-field to an intermediate store, e.g. storage with cathode ray tube
• CPC Class Codes: G06K 7/1443 locating of the code in an image

Abstract

The present invention provides for a bar code location and recognition processing system. The surface on which the bar code appears is optically scanned and converted to binary digital signals by a digital video processor. The output of the digital video processor is provided to a bar code image processor for location and reading of the bar code. The bar code is located by summing the "black" pixels in segments of predetermined width for each horizontal scan line, and determining the location of the "L" pattern characteristic of a digitized image of a bar code summed in this manner. Reading of the binary data corresponding to the bar code is carried out by summing the "black" pixels in each vertical scan line in a rectangular region generally corresponding to the location of the bar code within the digitized image, selecting a threshold value proportional to the average maxima of these sums, and, by determining which sums substantially exceed and which substantially fall below the threshold values, decode a binary code pattern corresponding to the bar code.

Claims

1. A bar code location and recognition system for locating a digitized image of a bar code, comprising:

means for converting an image of the surface of an object imprinted with a bar code pattern having at least two bars of different pitch to a digital image having an array of black and white pixels in rows and columns;

means for generating an L-shaped pattern characteristic of a digitized image of the bar code pattern when black pixels are summed along segments of each row containing a portion of the digital image of the bar code pattern; and

means for locating the coordinates of the L-shaped pattern in a region within the array of pixels containing the digitized image of the bar code pattern.

2. The bar code location and recognition system as set forth in claim 1 further comprising means for recognizing the digitized image of the bar code pattern, including:

means for counting the number of black pixels in each column within said region containing the digitized image of the bar code pattern; and

means for setting threshold values for the black pixel counts in order to determine from the counts the pattern of bars in the digitized image of the bar code pattern.

3. A bar code location and recognition system comprising means for recognizing the digitized image of the bar code pattern including:

means for converting an image of the surface of an object imprinted with a bar code pattern having at least two bars of different pitch to a digital image having an array of black and white pixels in rows and columns;

means for summing the number of black pixels in each column within the region containing the digitized image of the bar code pattern;

means for generating a first threshold value for distinguishing between peaks caused by the bars of the bar codes and peaks caused by background; and

means for generating additional threshold values to distinguish between peaks due to bars of different pitches to determine the pattern of bars in a digitized image of the bar code pattern.

4. A bar code pattern processor for locating and recognizing a digitized image of a full-bar half-bar code pattern generally oriented in a horizontal direction anywhere within an array of pixels containing the digitized image of a surface containing the full-bar halfbar pattern, each pixel being either black or white and the array having rows and columns of spaced pixels divided into vertical segments containing a plurality of columns, comprising:

means for locating the region within the array of pixels containing the digitized image of a full-bar halfbar code pattern including;

means for summing within sets of consecutive segments the black pixels in a set for generating an L-shaped pattern of the sums of the sets corresponding to the digitized full-bar half-bar code pattern,

means for comparing a set of consecutive segments from one horizontal row with sets of the same segments from adjacent horizontal rows to locate the changes in the sum of the sets due to the L-shaped pattern, and

means for generating from the sets of segments and rows containing the L-shape pattern coordinate data for the region in the array of pixels containing the full-bar half-bar code image; and

means for recognizing the pattern of full-bars and half-bars in the digitized image of the full-bar half-bar code pattern including;

means for counting the number of black pixels in a column within the boundaries of the region defined by the coordinate data, and

means for generating a first threshold value to distinguish between peaks in the number of black pixels caused by full-bars and half-bars and background noise, and a second threshold value to distinguish between peaks due to full-bars and peaks due to half-bars to establish the pattern of fullbars and half-bars in the digitized image of the fullbar half-bar code pattern.

5. A method of locating a digitized bar code image generally oriented in the horizontal direction anywhere within an array of pixels, said pixels comprising the digitized image of the surface of an object printed with a bar code pattern having bars of more than one pitch, said pixels being either black or white, said array having rows of spaced pixels and columns of spaced pixels and divided into vertical segments containing a plurality of columns, comprising the steps of:

(a) summing the number of black pixels found in a row within a set of vertical segments having at least one consecutive segment;

iterating step (a) across each row of said array by summing the number of black pixels in a set of consecutive vertical segments shifted by one segment from the previous set;

(c) determining from the sums generated by steps (a) and (b) relatively abrupt changes indicating the presence of a digitized image of a bar code pattern having bars of more than one pitch in the sums of black pixels from one set of segments on one row to the same set of segments on adjacent rows; and

(d) locating from the position of the identified abrupt changes the region of the array of pixels containing the digitized image of the bar code pattern.

6. The method of locating a digitized bar code image as described in claim 5, further comprising the steps of:

(a) summing the pixels in each vertical column from the bottom of said region to the top of said region;

(b) locating those columns in which peaks in the number of black pixels occur;

(c) generating a first threshold value for distinguishing between peaks caused by the bars of the bar codes and peaks caused by the background; and

(d) generating additional threshold values to distinguish between peaks due to bars of different pitches to determine the pattern of parts in the digitized image of the bar code pattern.

7. A method of recognizing a digitized bar code image in a region generally oriented in the horizontal direction anywhere within an array of pixels, said pixels comprising the digitized bar code image of the surface of an object printed with a bar code pattern having bars of more than one pitch, and said pixels being either black or white, said array having rows and columns of spaced pixels, comprising the steps of:

(a) summing the black pixels in each vertical column from the bottom of the region containing the digitized bar code image of the bar code pattern to the top of the region;

(g) generating a first threshold value for distinguishing between peaks in the number of black pixels caused by the bars of the bar codes and peaks caused by the background; and

(c) generating additional threshold values to distinguish between peaks in the number of black pixels due to bars of different pitches in order to determine the pattern of bars in the digitized bar code image of the bar code pattern.

8. Apparatus for locating a bar code pattern on an object, comprising:

means for converting an image of the surface of the object imprinted with the bar code pattern to a digital image having an array of black and white pixels in rows and columns;

means for generating a horizontal histogram from the rows of pixels characteristic of the digital image of the surface of the object, the generated horizontal histogram for the bar code having a characteristic L-shaped pattern; and

means for locating, from the generated horizontal histogram, a region within the array of pixels containing the digitized image of the bar code pattern by locating areas of the horizontal histogram having the characteristic L-shaped pattern.

9. Apparatus for locating a bar code pattern as set forth in claim 8 wherein said means for generating includes means for horizontally summing the number of black pixels in a predetermined number of successive segments of the digital image of the object.

10. Apparatus for locating a bar code pattern as set forth in claim 9 wherein said means for generating further includes logic circuits for generating the horizontal histogram coincident with the means for converting the image of the surface of the object to the digital image.

11. The method of locating a digitized bar code image having horizontal and vertical direction anywhere within an array of pixels, the pixels generated by digitizing the image of the surface of an object having been printed with a bar code pattern, said pixels being either black or white and the array having rows of spaced pixels arranged in a horizontal direction and columns of spaced pixels arranged in a generally vertical direction such that the array includes a plurality of rows and a plurality of columns, comprising the steps of:

generating a horizontal histogram from the rows of pixels characteristic of the digitized image of the surface of the object, the generated histogram for a bar code having an L-shaped pattern; and

locating within the array of pixels containing the digitized image of the bar code pattern an area of the generated horizontal histogram containing the L-shaped pattern.

12. The method of locating a digitized bar code image as set forth in claim 11 wherein the step of generating a horizontal histogram includes the steps of horizontally summing the number of black pixels in a predetermined number of successive segments in a row of the digitized image of the object.

13. The method of locating a digitized bar code image as set forth in claim 12 wherein the step of locating an area within the generated horizontal histogram includes the step of identifying abrupt changes in the in the summed total of black pixels for consecutive rows for a given segments of the horizontal histogram.

14. A bar code pattern processor for locating and recognizing a digitized image of the bar code pattern having a generally horizontal direction and a generally vertical direction anywhere within an array of pixels containing the digitized image of a surface containing the bar code pattern, each pixel being either black or white, the array having rows and columns of spaced pixels, comprising:

means for generating a horizontal histogram characteristic of the digitized image of the bar code pattern from the rows of pixels, each row containing a portion of the digitized image of the bar code pattern;

means for generating a vertical histogram characteristic of the digitized image of the bar code pattern from the columns of pixels, each column containing a portion of the digitized image of the bar code pattern;

means for locating coordinates of the horizontal histogram in a region within the array of pixels containing the digitized image of the bar code pattern; and

means for testing the vertical histogram to identify the validity thereof for recognition of the digitized image.

15. A bar code pattern processor as set forth in claim 14 wherein said means for generating the horizontal histogram includes means for summing the black pixels in the rows of the array in a predetermined number of successive segments of the bar code pattern.

16. A bar code pattern processor as set forth in claim 14 wherein said means for locating includes means for identifying a horizontal histogram with a particular bar code pattern.

17. A bar code pattern processor as set forth in claim 14 wherein the array of pixels includes a plurality of digitized images, further comprising:

means for prioritizing of the plurality of bar code patterns in the array to identify the pattern to be located.