Digital imaging-based bar code symbol reading system employing image cropping pattern generator and automatic cropped image processor

• US 7,464,877 B2
• Filed: 04/20/2006
• Issued: 12/16/2008
• Est. Priority Date: 11/13/2003
• Status: Expired due to Term

• Current Assignee: Metrologic Instruments Incorporated (Honeywell International Inc.)
• Original Assignee: Metrologic Instruments Incorporated (Honeywell International Inc.)
• Inventors: Zhu, Xiaoxun, Au, Ka Man, Kotlarsky, Anatoly
• Primary Examiner(s): Kim; Ahshik
• Application Number:
  US11/408,268
• Publication Number:
  US 20070040035A1
• Time in Patent Office: 971 Days
• Field of Search: 235/462.45, 235/462.01, 235/462.09, 235/462.24, 235/462.42
• US Class Current: 235/462.45
• CPC Class Codes: G06K 7/10683 Arrangement of fixed elements
• CPC Class Codes: G06K 7/10712 Fixed beam scanning
• CPC Class Codes: G06K 7/10722 Photodetector array or CCD scanning
• CPC Class Codes: G06K 7/10732 Light sources
• CPC Class Codes: G06K 7/10801 Multidistance reading
• CPC Class Codes: G06K 7/10831 Arrangement of optical elements, e.g. lenses, mirrors, prisms optical elements per se G02B
• CPC Class Codes: G06K 7/10851 Circuits for pulse shaping, amplifying, eliminating noise signals, checking the function of the sensing device basic electronic circuitry H03

Abstract

Disclosed is a method of and apparatus for dynamically and adaptively controlling system control parameters (SCPs) in a multi-mode image capture and processing system, wherein (i) automated real-time exposure quality analysis of captured digital images is automatically performed in a user-transparent manner, and (ii) system control parameters (e.g. illumination and exposure control parameters) are automated reconfigured based on the results of such exposure quality analysis, so as to achieve improved system functionality and/or performance in diverse environments.

Claims

1. A hand-supportable digital imaging-based bar code symbol reading system comprising:

a hand-supportable housing;

an image formation and detection subsystem including (i) image formation optics for producing a field of view (FOV) upon an object to be imaged, and (ii) an area-type image sensing array for detecting imaged light reflected off the object during illumination operations in an image capture mode, and producing a 2D image of the illuminated object;

a LED-based illumination subsystem having an LED illumination array for producing a field of illumination within said FOV of said image formation and detection subsystem during said image capture mode;

an image cropping pattern generator for generating a visible illumination-based image cropping pattern (ICP) projected within said FOV of said image formation and detection subsystem;

an object presence and range detection subsystem for producing an object detection field within said FOV of said image formation and detection subsystem;

an automatic light exposure measurement and illumination control subsystem for measuring illumination levels in a central portion of said FOV and controlling the operation of said LED-based illumination subsystem;

an image capturing and buffering subsystem for capturing and buffering 2D images detected by said image formation and detection subsystem;

a cropped image locating module for processing said captured and buffered 2D images so as to locate the image region corresponding to said ICP, and cropping said image region;

a perspective correction and scaling module for processing said cropped image region and correcting the perspective of said cropped image region and scaling the perspective corrected image to a predetermined pixel image size suitable for decode-processing;

an image-processing based bar code symbol reading subsystem for decode-processing cropped and scaled images generated by said perspective correction and scaling module, and reading 1D and 2D bar code symbols represented in said captured and buffered 2D images; and

an input/output subsystem for outputting processed image data to an external host system or other information receiving or responding device.

2. The hand-supportable digital imaging-based bar code symbol reading system of claim 1, wherein said image cropping pattern generator comprises a visible laser diode (VLD) and a pair of flat-convex lenses arranged before the VLD, for generating and projecting a two dot image cropping pattern (ICP) within said FOV of said image formation and detection subsystem.

3. The hand-supportable digital imaging-based bar code symbol reading system of claim 2, wherein said pair of flat-convex lenses focus naturally diverges light rays from said VLD into two substantially parallel beams of laser illumination, thereby producing said two (2) dot image cropping pattern (ICP) within said FOV of said image formation and detection subsystem.

4. The hand-supportable digital imaging-based bar code symbol reading system of claim 1, wherein said image cropping pattern generator comprises a visible laser diode (VLD) and a biconical lens arranged before said VLD, and four flat-convex lenses arranged in four corners, for generating and projecting a four (4) dot image cropping pattern (ICP) within said FOV of said image formation and detection subsystem.

5. The hand-supportable digital imaging-based bar code symbol reading system of claim 1, wherein said image cropping pattern generator comprises a visible laser diode (VLD) and a light diffractive optical (DOE) element forming an optical assembly for generating and projecting a four (4) dot image cropping pattern (ICP) within said FOV of said image formation and detection subsystem.

6. A digital image capture and processing engine comprising:

an image formation and detection subsystem having image formation optics for producing a field of view (FOV) upon an object to be imaged, and an area-type image sensing array for detecting imaged light reflected off the object during illumination operations in an image capture mode, and producing a 2D image of the illuminated object;

a LED-based illumination subsystem having an LED illumination array for producing a field of illumination within said FOV of said image formation and detection subsystem during said image capture mode;

an optical waveguide component for measuring light intensity within a central portion of FOV said image formation and detection subsystem, for purposes of automatic illumination control of the LED illumination array illuminating said FOV of said image formation and detection subsystem; and

an image cropping pattern generator for generating a visible illumination-based image cropping pattern (ICP) projected within said FOV of said image formation and detection subsystem;

an image capturing and buffering subsystem for capturing and buffering 2D images detected by said image formation and detection subsystem;

a cropped image locating module for processing said captured and buffered 2D images so as to locate the image region corresponding to said ICP, and cropping said image region;

a perspective correction and scaling module for processing said cropped image region and correcting the perspective of said cropped image region and scaling the perspective corrected image to a predetermined pixel image size suitable for decode-processing; and

an image-processing based bar code symbol reading subsystem for decode-processing cropped images generated by said perspective correction and scaling module, and reading 1D and 2D bar code symbols represented in said captured and buffered 2D images; and

an input/output subsystem for outputting processed image data to an external host system or other information receiving or responding device.

7. The digital image capture and processing engine of claim 6, wherein said optical waveguide component is a subcomponent within an automatic light exposure measurement and illumination control subsystem for measuring illumination levels in said central portion of said FOV and controlling the operation of said LED-based illumination subsystem.

8. The digital image capture and processing engine of claim 7, which further comprises:

an object presence and range detection subsystem for producing an object detection field within said FOV of said image formation and detection subsystem.

9. A hand-supportable digital imaging-based bar code symbol reading system comprising:

a hand-supportable housing;

an image formation and detection subsystem including (i) image formation optics for producing a field of view (FOV) upon an object to be imaged, and (ii) an area-type image sensing array for detecting imaged light reflected off the object during illumination operations in an image capture mode, and producing a 2D image of the illuminated object;

a LED-based illumination subsystem having an LED illumination array for producing a field of illumination within the FOV of said image formation and detection subsystem during said image capture mode;

an image cropping pattern generator for generating a visible illumination-based image cropping pattern (ICP) projected within said FOV of said image formation and detection subsystem;

an automatic light exposure measurement and illumination control subsystem for measuring illumination levels in a predetermined portion of said FOV and controlling the operation of said LED-based illumination subsystem;

an image capturing and buffering subsystem for capturing and buffering 2D images detected by said image formation and detection subsystem;

a cropped image locating module for processing captured and buffered images so as to locate the image region corresponding to said ICP, and cropping said image region;

a predecode-processing module for processing said cropped image region and scaling the cropped image region to a predetermined pixel image size suitable for decode-processing;

an image-processing based bar code symbol reading subsystem for decode-processing cropped and scaled images generated by said predecode-processing module, and reading one or more 1D and/or 2D bar code symbols represented in said captured and buffered 2D images; and

an input/output subsystem for outputting processed image data and the like to an external host system or other information receiving or responding device.

10. The hand-supportable digital imaging-based bar code symbol reading system of claim 9, wherein said predecode-processing module further comprises an image processing component for processing said cropped image region and correcting the perspective of said cropped image region and thereafter scaling the perspective corrected image to a predetermined pixel image size suitable for decode-processing.

11. The hand-supportable digital imaging-based bar code symbol reading system of claim 9, which further comprises an object presence and range detection subsystem for producing an object detection field within the FOV of said image formation and detection subsystem.

12. The hand-supportable digital imaging-based bar code symbol reading system of claim 9, wherein said image cropping pattern generator comprising a visible laser diode (VLD) and a pair of flat-convex lenses arranged before said VLD, for generating and projecting a two dot image cropping pattern (ICP) within the field of view of said image formation and detection subsystem.

13. The hand-supportable digital imaging-based bar code symbol reading system of claim 9, wherein said image cropping pattern generator comprises said pair of flat-convex lenses focusing naturally diverging light rays from a visible laser diode (VLD) into two substantially parallel beams of laser illumination, thereby producing a two (2) dot image cropping pattern (ICP) within the field of view of said image formation and detection subsystem.

14. The hand-supportable digital imaging-based bar code symbol reading system of claim 9, wherein said image cropping pattern generator comprises a visible laser diode (VLD) and a biconical lens arranged before said VLD, and four flat-convex lenses arranged in four corners, for generating and projecting a four (4) dot image cropping pattern (ICP) within said FOV of said image formation and detection subsystem.

15. The hand-supportable digital imaging-based bar code symbol reading system of claim 9, wherein said image cropping pattern generator comprises a visible laser diode (VLD) and a light diffractive optical (DOE) element forming an optical assembly for generating and projecting a four (4) dot image cropping pattern (ICP) within the field of view of said image formation and detection subsystem.

16. The hand-supportable digital imaging-based bar code symbol reading system of claim 9, wherein said automatic light exposure measurement and illumination control subsystem further comprises an optical waveguide component for measuring light intensity within said predetermined portion of said FOV.

17. A digital image capture and processing engine comprising:

an image formation and detection subsystem having image formation optics for producing a field of view (FOV) upon an object to be imaged, and an area-type image sensing array for detecting imaged light reflected off the object during illumination operations in an image capture mode, and producing a 2D image of the illuminated object;

a LED-based illumination subsystem having an LED illumination array for producing a field of illumination within said FOV of said image formation and detection subsystem during said image capture mode;

an automatic light exposure measurement and illumination control subsystem for measuring illumination levels in a predetermined portion of said FOV and controlling the operation of said LED-based illumination subsystem;

wherein said automatic light exposure measurement and illumination control subsystem further includes an optical waveguide component for measuring light intensity within said predetermined portion of said FOV of said image formation and detection subsystem;

an image cropping pattern generator for generating a visible illumination-based image cropping pattern (ICP) projected within said FOV of said image formation and detection subsystem;

an image capturing and buffering subsystem for capturing and buffering 2D images detected by said image formation and detection subsystem;

a cropped image locating module for processing said captured and buffered 2D images so as to locate the image region corresponding to said ICP, and cropping said image region;

a predecode-processing module for processing said cropped image region and scaling the cropped image region to a predetermined pixel image size suitable for decode-processing;

an image-processing based bar code symbol reading subsystem for decode-processing cropped images generated by said predecode-processing module, and reading one or more 1D and/or 2D bar code symbols represented in said captured and buffered 2D images; and

an input/output subsystem for outputting processed image data to an external host system or other information receiving or responding device.

18. The digital image capture and processing engine of claim 17, wherein said predecode-processing module further comprises an image processing component for processing said cropped image region and correcting the perspective of said cropped image region and thereafter scaling the perspective corrected image to a predetermined pixel image size suitable for decode-processing.

19. The digital image capture and processing engine of claim 17, which further comprises:

an object presence and range detection subsystem for producing an object detection field within said FOV of said image formation and detection subsystem.

20. A digital image capture and processing system comprising:

a housing having a light transmission aperture;

an image formation and detection subsystem, disposed in said housing, and having (i) image formation optics for producing and projecting a field of view (FOV) through said light transmission aperture and upon an object to be imaged, and (ii) an area-type image sensing array for detecting imaged light reflected off the object during illumination operations in an image capture mode, and producing a 2D image of the illuminated object;

an illumination subsystem, disposed in said housing, and having an illumination array for producing a field of illumination within said FOV of said image formation and detection subsystem during said image capture mode;

an automatic illumination control subsystem, disposed in said housing, for controlling the operation of said illumination subsystem;

an image cropping pattern generator, disposed in said housing, for generating a visible illumination-based image cropping pattern (ICP) projected within said FOV of said image formation and detection subsystem;

an image capturing and buffering subsystem, disposed in said housing, for capturing and buffering 2D images detected by said image formation and detection subsystem;

a cropped image locating module, disposed in said housing, for processing said captured and buffered 2D images so as to locate the image region corresponding to said ICP, and cropping said image region;

a predecode-processing module, disposed in said housing, for processing said cropped image region and scaling the cropped image region to a predetermined pixel image size suitable for decode-processing;

an image processing subsystem for decode-processing cropped images scaled by said predecode-processing module, and reading one or more 1D and/or 2D code symbols represented in said captured and buffered 2D images; and

an input/output subsystem for outputting processed image data to an external host system or other information receiving or responding device.

21. The digital image capture and processing system of claim 20, wherein said predecode-processing module further comprises an image processing component for processing said cropped image region and correcting the perspective of said cropped image region and thereafter scaling the perspective corrected image to a predetermined pixel image size suitable for decode-processing.

22. The digital image capture and processing system of claim 20, which further comprises:

an object detection subsystem, disposed in said housing, for producing an object detection field within the FOV of said image formation and detection subsystem.

23. The digital image capture and processing system of claim 20, wherein said image cropping pattern generator comprises one or more light sources for generating one or more visible light beams used to generate said visible illumination-based image cropping pattern (ICP).

24. The digital image capture and processing system of claim 23, wherein said image cropping pattern generator further comprises at least one optical component selected from the group consisting of a light refractive element, a light diffractive element, and a light reflective element.

25. The digital image capture and processing system of claim 20, wherein said housing is a hand-supportable housing.

26. The digital image capture and processing system of claim 20, wherein said housing is a countertop-supportable housing.

27. The digital image capture and processing system of claim 20, wherein said 1D and/or 2D code symbols are selected from the group consisting of 1D bar code symbols, 2D bar code symbols and data matrix symbols.

28. The digital image capture and processing system of claim 20, wherein said illumination array comprises an array of light emitting diodes (LEDs).