Optical Code Scanner Optimized for Reading 2D Optical Codes

• US 20150144693A1
• Filed: 11/22/2013
• Published: 05/28/2015
• Est. Priority Date: 11/22/2013
• Status: Active Grant

• Current Assignee: NCR Voyix Corporation
• Original Assignee: NCR Corporation (NCR Voyix Corporation)
• Inventors: Kwan, Sik Piu, Li, Jun
• Granted Patent: US 9,147,095 B2
• Time in Patent Office: Days
• US Class Current: 235/437
• CPC Class Codes: G06K 7/10722 Photodetector array or CCD scanning
• CPC Class Codes: G06K 7/1096 the scanner having more than one scanning window, e.g. two substantially orthogonally placed scanning windows for integration into a check-out counter of a super-market
• 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: G06K 7/1465 using several successive scans of the optical code
• CPC Class Codes: G06K 7/1473 error correction
• CPC Class Codes: G06K 7/1478 adapting the threshold for pixels in a CMOS or CCD pixel sensor for black and white recognition

Abstract

An optical code scanner is presented that includes image capture technology to read optical codes. The optical code scanner captures an image of an optical code and then generates multiple reduced resolution versions of the image. Multiple techniques are applied to the different images to identify a region of interest, enhance the contrast of the image, perform a non-linear local geometrical distortion correction and minimize the spatial resolution required to read the optical code. The techniques reduce the raw processing power and time required to identify and read an optical code.

Claims

1. A method of operating an optical code scanner implemented by a digital processor within the optical code scanner, the method comprising:

capturing an image from the item scanning area of the optical code scanner;

generating a sequence of reduced resolution images from the captured image wherein each successive generated image has a lower resolution than the prior image;

enhancing the contrast of the lowest resolution generated image not previously enhanced to improve the quality of the image;

identifying a region of interest in the enhanced generated image with the highest resolution wherein the region of interest includes an optical code candidate;

modifying a portion of the captured image that corresponds to the identified region of interest to correct for geometrical distortion; and

recovering optical code data from the optical code candidate located in the modified portion of the captured image.

2. The method of claim 1, wherein generating a sequence of reduced resolution images includes generating successive images that each have a 4×

reduction in image resolution from the prior image.

3. The method of claim 2, wherein four reduced resolution images are generated.

4. The method of claim 1, wherein to correct for geometrical distortion further comprises correcting for local non-linear geometrical distortion of the optical code candidate.

5. The method of claim 1, further comprising:

extracting a foreground image from the enhanced generated image with the highest resolution using intra-class variance;

and wherein identifying the region of interest includes using the extracted foreground image to identify the optical code candidate.

6. The method of claim 5, further comprising:

determining the region of interest cannot be identified and then repeating the enhancing, the extracting and the identifying steps until all generated images have been enhanced;

determining the region of interest cannot be identified and all generated images have been enhanced and then repeating the capturing, the generating, the enhancing and the identifying steps.

7. The method of claim 1, further comprising:

performing a minimum spatial resolution function on the region of interest; and

wherein recovering optical code data includes using data generated by a minimum spatial resolution function.

8. The method of claim 1, further comprising:

transmitting the recovered optical code data on an external network.

9. An optical code scanner comprising:

an image capture device arranged to receive images from an item scanning area of the optical code scanner;

a communications device connected to an external network;

a memory including software; and

a processor in communication with the image capture device, the communications device and the memory and where the software when executed by the processor causes the processor to perform the following steps;

capture an image from the item scanning area of the optical code scanner;

generate a sequence of reduced resolution images from the captured image wherein each successive generated image has a lower resolution than the prior image;

enhance the contrast of the lowest resolution generated image not previously enhanced to improve the quality of the image;

identify a region of interest in the enhanced generated image with the highest resolution wherein the region of interest includes an optical code candidate;

modify a portion of the captured image that corresponds to the identified region of interest to correct for geometrical distortion; and

recover optical code data from the optical code candidate located in the modified portion of the captured image.

10. The method of claim 9, wherein generating a sequence of reduced resolution images includes generating successive images that each have a 4×

reduction in image resolution from the prior image.

11. The method of claim 10, wherein four reduced resolution images are generated.

12. The method of claim 9, wherein to correct for geometrical distortion further comprises correcting for local non-linear geometrical distortion of the optical code candidate.

13. The method of claim 9, further comprising:

extracting a foreground image from the enhanced generated image with the highest resolution using intra-class variance;

and wherein identifying the region of interest includes using the extracted foreground image to identify the optical code candidate.

14. The method of claim 9, further comprising:

performing a minimum spatial resolution function on the region of interest; and

wherein recovering optical code data includes using data generated by the minimum spatial resolution function.

15. A method of operating an optical code scanner implemented by a digital processor within the optical code scanner, the method comprising:

capturing an image from the item scanning area of the optical code scanner;

generating a sequence of reduced resolution images from the captured image wherein each successive generated image has a lower resolution than the prior image;

enhancing the contrast of the lowest resolution generated image not previously enhanced to improve the quality of the image;

examining the highest resolution generated image that has been enhanced to determine if a region of interest exists wherein the region of interest includes an optical code candidate and when a region of interest is determined not to exist, repeating the enhancing and examining steps until a region of interest is found or all enhanced generated images have been examined and when a region of interest is determined to exist, performing the modifying and recovering steps;

determining when no region of interest has been found to exist and all enhanced generated images have been examined for a region of interest and then repeating the capturing, the generating, the enhancing and examining steps;

modifying a portion of the captured image that corresponds to the identified region of interest to correct for geometrical distortion; and

recovering optical code data from the optical code candidate located in the modified portion of the captured image.

16. The method of claim 15, wherein generating a sequence of reduced resolution images includes generating successive images that each have a 4×

reduction in image resolution from the prior image.

17. The method of claim 16, wherein four reduced resolution images are generated.

18. The method of claim 15, wherein to correct for geometrical distortion further comprises correcting for local non-linear geometrical distortion of the optical code candidate.

19. The method of claim 15, further comprising:

extracting a foreground image from the enhanced generated image with the highest resolution using intra-class/between-class variance;

and wherein determining the existence of the region of interest includes using the extracted foreground image to identify the optical code candidate.

20. The method of claim 15, further comprising:

performing a minimum spatial resolution function on the region of interest; and

wherein recovering optical code data further includes using data generated by the minimum spatial resolution function.