Methods and apparatus for reading bar code identifications

• US 7,175,090 B2
• Filed: 08/30/2004
• Issued: 02/13/2007
• Est. Priority Date: 08/30/2004
• Status: Expired due to Fees

• Current Assignee: Cognex Technology & Investment Corporation (Cognex Corporation)
• Original Assignee: Cognex Technology & Investment Corporation (Cognex Corporation)
• Inventors: Nadabar, Sateesha G.
• Primary Examiner(s): Le; Thien M.
• Assistant Examiner(s): Labaze; Edwyn
• Application Number:
  US10/930,056
• Publication Number:
  US 20060043186A1
• Time in Patent Office: 897 Days
• Field of Search: 235/462.01, 235/462.1, 235/462.09, 235/462.07
• US Class Current: 235/462.1
• CPC Class Codes: G06K 2207/1017 Programmable
• CPC Class Codes: G06K 7/14 using light without selection of wavelength, e.g. sensing reflected white light G06K7/10831 - G06K7/1097 take precedence

Abstract

The invention provides methods and appartaus for analysis of images of two-dimensional (2D) bar codes in which a model that has proven successful in decoding of a prior 2D image of a 2D bar code is utilized to speed analysis of images of subsequent 2D bar codes. In its various aspects, the invention can be used in analyzing conventional 2D bar codes, e.g., those complying with Maxicode and DataMatrix standards, as well as stacked linear bar codes, e.g., those utilizing the Codablock symbology. Bar code readers, digital data processing apparatus and other devices according to the invention be used, by way of non-limiting example, to decode bar codes on damaged labels, as well as those screened, etched, peened or otherwise formed on manufactured articles (e.g., from semiconductors to airplane wings). In addition to making bar code reading possible under those conditions, devices utilizing such methods can speed bar code analysis in applications where multiple bar codes of like type are read in succession and/or are read under like circumstances—e.g., on the factory floor, at point-of-sale locations, in parcel deliver and so forth. Such devices can also speed and/or make possible bar code analysis where in applications where multiple bar codes read from a single article—e.g., as in the case of a multiply-encoded airplane propellor or other milled parts. The invention also provides methods and apparatus for optical character recognition and other image-based analysis paralleling the above.

Claims

1. A method of reading two-dimensional (2D) bar codes of the type having a machine-readable component and, optionally, having a human-readable component, where the machine-readable component comprises a plurality of bars, dots or other machine-readable symbols (collectively, “

machine-readable symbols”

) encoding data, the method comprising;

(A) providing multiple models, each discerned from a successful respective decode of a 2D image of a 2D bar code,

(B) analyzing a 2D image of a further 2D bar code to decode the machine-readable symbols thereof, the analyzing step including (i) using a model provided in step (A) to determine the machine-readable symbols of the further 2D bar code in the image thereof, where that model is used in lieu of one discerned from the image of the further 2D bar code, (ii) testing for error data so decoded from the machine-readable symbols of the further 2D bar code,

(B) responding to an unfavorable result in step (B)(ii) by executing step (C) with each of one or more additional models provided in step (A),

(D) responding to an unfavorable result in execution of step (B)(ii) per step (C) by analyzing said 2D image of said further 2D bar code to decode the machine-readable symbols thereof, the analyzing step including (i) discerning from that image a model of representation of the further 2D bar code therein, where that model comprises one or more characteristics of that representation and (ii) testing for error data so decoded from the machine-readable symbols of the further 2D bar code,

(E) responding to a favorable result in step (D)(ii) by using said model discerned in step (D)(i) in further execution of one or more of steps (B) and (C), and

(F) where the 2D image of the further 2D bar code may comprise all or portions of the same 2D image or images from which the models were discerned.

2. The method of claim 1, wherein step (A) comprises analyzing a 2D image of a first 2D bar code to decode the machine-readable symbols thereof, the analyzing step including (i) discerning from that image a said model of representation of the first 2D bar code therein, where that model comprises one or more characteristics of that representation and (ii) testing for en-or data so decoded from the machine-readable symbols of the first 2D bar code.

3. The method of claim 2, wherein step (A) includes discerning a model having one or more characteristics that are geometric characteristics of the first 2D bar code in the image thereof and which one or more characteristics are not expected to vary substantially as between the image of the first 2D bar code and the image of the further 2D bar code.

4. The method of claim 2, wherein step (A) includes discerning from the image of the first 2D bar code a model having one or more characteristics that are any of intensity and/or contrast of the first 2D bar code in the image.

5. The method of claim 4, wherein the one or more characteristics are not expected to vary substantially from image-to-image and under the circumstances in which those images are acquired.

6. The method of claim 2, wherein the model step (A) includes discerning from the image of the first 2D bar code a model having one or more characteristics that are not expected to vary substantially as between the image of the first 2D bar code, the image of the further 2D bar code and the images of one or more further bar codes.

7. The method of claim 1, comprising limiting a period of time and/or expenditure of other digital data processing resources in performing step (B)(i).

8. The method of claim 7, wherein the geometric characteristics include the height and/or width of at least the machine-readable component of the first 2D bar code in the image thereof.

9. The method of claim 7, wherein the geometric characteristics include a number of rows and/or columns in the machine-readable component of the first 2D bar code.

10. The method of claim 7, wherein the geometric characteristics include a geometry of symbols that makes up the bar code.

11. The method of claim 7, wherein the geometric characteristics include an imaging geometry of the first 2D bar code in the image thereof.

16. A digital data processing apparatus operating in an accord with the method of any of claims 1 and 12.

17. A bar code reader operating in an accord with the method of any of claims 1 and 12.

12. A method of reading two-dimensional (2D) bar codes of the type having a machine-readable component and, optionally, having a human-readable component, where the machine-readable component comprises a plurality of bars, dots or other machine-readable symbols (collectively, “

machine-readable symbols”

) encoding data, the method comprising;

(A) acquiring a 2D image of each of multiple first 2D bar codes,

(B) analyzing the 2D image of each of the first 2D bar codes to decode the machine-readable symbols thereof, the analyzing step including (i) discerning from among a plurality of possibilities a model of representation of the first 2D bar code in the image thereof, where that model comprises one or more geometric characteristics of that representation that are expected to be substantially invariant as among images of a plurality of bar codes, and (ii) testing for error data so decoded from the machine-readable symbols

(C) acquiring one or more further 2D images of one or more further 2D bar codes, where the 2D images of the first 2D bar codes and the 2D images of the further 2D bar code may comprise all or portions of one or more 2D images,

(D) analyzing one or more of the 2D images of a said further 2D bar code to decode the machine-readable symbols thereof, the analyzing step including (i) using a said model discerned in step (B)(i) to decode the machine-readable symbols of that further 2D bar code in the image thereof, where that model is used in lieu of ones discerned from that image of the further 2D bar code itself, (ii) testing for error data so decoded from the machine-readable symbols of the further 2D bar code,

(E) responding to an unfavorable result in step (D)(ii) by executing step (D) with each of one or more additional models discerned in step B(i)

(F) responding to unfavorable result in execution of step (D)(ii) per step (E) by executing step (B) with one or more 2D images of said further 2D bar code,

(G) responding to favorable testing in execution of step (B)(ii) per step (F) by using a model discerned in execution of step (B)(i) per step (F) in further execution of one or more of steps (D) and (E).

13. The method of claim 12, wherein steps (A) and (C) including acquiring the images from a common image acquisition device.

14. The method of claim 13, wherein the common image acquisition device is any of a fixed and hand-held device.

15. The method of claim 12 comprising limiting a period of time and/or expenditure of other digital data processing resources in performing step (D)(i).

18. A method of optical character recognition comprising;

(A) providing multiple models, each discerned from a successful respective recognition of sequence of one or more characters in a two-dimensional (2D) image thereof,

(B) analyzing an image of a further character sequence comprising one or more characters, the analyzing step including using a model provided in step (A) to discern the characters that make up the further character sequence, where that model is used in lieu of one discerned from the image of the further character sequence itself, and

(C) responding to an absence of success in step (B) by re-executing that step with each of one or more additional models provided in step (A)

(D) responding to an absence of success in re-execution of step (B) per step (C) by analyzing one or more 2D images of said further character sequence to decode the characters therein, the analyzing step including (i) discerning from that image a model of representation of the further character sequence in that image, where that model comprises one or more characteristics of that representation and (ii) testing for error characters so decoded from the machine-readable symbols of the further character sequence,

(E) responding to a favorable result in step (D)(ii) by using a model discerned in step (D)(i) in further execution of one or more of steps (B) and (C).

19. The method of claim 18, wherein step (A) comprises analyzing a 2D image of a first character sequence to decode the characters therein, the analyzing step including (i) discerning from that image a said model of representation of the first character sequence in that image, where that model comprises one or more characteristics of that representation and (ii) testing for error characters so decoded from the first character sequence.

20. The method of claim 19, wherein step (A) includes discerning a model having one or more characteristics that are geometric characteristics of the first character sequence in the image thereof and which one or more characteristics are not expected to vary substantially as between the image of the first character sequence and the image of the second character sequence.

21. The method of claim 20, wherein the geometric characteristics include the height and/or width of the characters in the first character sequence in the image thereof.

22. The method of claim 21, wherein the geometric characteristics include a geometry of characters that make up the first character sequence.

23. The method of claim 22, wherein the geometric characteristics include an imaging geometry of the first character sequence in the image thereof.

24. The method of claim 19, wherein step (A) includes discerning from the image of the first character sequence a model having one or more characteristics that are any of intensity and/or contrast of the first character sequence in the image.

25. The method of claim 19, wherein the model step (A) includes discerning from the image of the first character sequence a model having one or more characteristics that are not expected to vary substantially as between the image of the first character sequence and the image of the further character sequence.

26. A digital data processing apparatus operating in an accord with the method of any of claims 18–

25.

27. A method of optical character recognition comprising:

(A) providing multiple models, each discerned from a successful analysis of one or more symbols in a respective two-dimensional (2D) image thereof,

(B) analyzing an image of a further sequence comprising one or more symbols, the analyzing step including (i) using a model provided in step (A) to discern the symbols that make up the further character sequence, where that model is used in lieu of one discerned from the image of the further character sequence itself.

(C) responding to an absence of success in step (B) by re-executing that step with each of one or more additional models provided in step (A)

(D) responding to an absence of success in re-execution of step.(B) per step (C) by analyzing one or more 2D images of said further character sequence to decode the characters therein, the analyzing step including (i) discerning from that image a model of representation of the further character sequence in that image, where that model comprises one or more characteristics of that representation and (ii) testing for characters decoded from the further character sequence, and

(E) responding to a favorable result in step (D)(ii) by using a model discerned in step (D)(i) in further execution of one or more of steps (B) and (C).