Method of dynamically controlling illumination and image capturing operations in a digital image capture and processing system

• US 20070199998A1
• Filed: 01/31/2007
• Published: 08/30/2007
• Est. Priority Date: 11/13/2003
• Status: Active Grant

• Current Assignee: Anatoly Kotlarsky, Daniel Hu, Ka Au, Mark Meagher, Michael Veksland, Richard Hou, Timothy Good, Xiaoxun Zhu
• Original Assignee: Anatoly Kotlarsky, Daniel Hu, Ka Au, Mark Meagher, Michael Veksland, Richard Hou, Timothy Good, Xiaoxun Zhu
• Inventors: Zhu, Xiaoxun, Veksland, Michael, Good, Timothy, Kotlarsky, Anatoly, Hou, Richard, Meagher, Mark, Hu, Daniel, Au, Ka
• Granted Patent: US 7,540,425 B2
• Time in Patent Office: Days
• 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

A digital image capture and processing system employing automated real-time analysis of digital image exposure quality to automatically reconfigure system control parameters, and dynamically control illumination and imaging operations within the digital image capture and processing system.

Claims

1. A method of dynamically controlling illumination and imaging operations within a digital image capture and processing system, said method comprising the steps of:

(a) in the presence of an object to be illuminated and imaged, providing a digital image capture and processing system including

(1) a digital image formation and detection subsystem having an area-type image detection array for detecting digital images of the object within a field of view (FOV) during object illumination and imaging operations, and being characterized by one or more system control parameters (SCPs) selected from a first group of SCPs,

(2) an illumination subsystem having an illumination array for producing and projecting a field of illumination within said FOV during said object illumination and imaging operations, and being characterized by one or more system control parameters selected from a second group of SCPs,

(3) an automatic illumination control subsystem for controlling said illumination array during said object illumination and imaging operations,

(4) a digital image capturing and buffering subsystem for capturing and buffering said digital images in memory, during said object illumination and imaging operations,

(5) a digital image processing subsystem for processing said digital images and (i) measuring the exposure quality of said digital images, and (ii) reading one or more 1D and/or 2D code symbols graphically represented in said digital images, and producing symbol character data representative of said read one or more 1D and/or 2D code symbols,

(6) an input/output subsystem for transmitting said symbol character data to an external host system or other information receiving or responding device, and

(7) a system control system for managing in memory, exposure quality threshold (EQT) parameters and said SCPs;

(b) initializing said digital image capture and processing system by setting an initial set of system control parameters (SCP);

(c) resetting a SCP reconfiguration (SCPR) flag to a first value, indicating that said digital image capture and processing system should not be reconfigured;

(d) calculating and setting exposure quality threshold (EQT) parameters in said digital image capture and processing system; and

(e) upon the occurrence of a trigger event signal generated within said digital image capture and processing system, performing the following operations;

(1) if said SCPR flag is set to a second value, indicative that said system should be reconfigured, then reconfiguring said digital image capture and processing system using a new set of SCPs;

otherwise, maintaining said system using current set of SCPs;

(2) illuminating said object using the method of illumination indicated by the current set of SCPs, and capturing a digital image thereof;

(3) analyzing the captured digital image for exposure quality;

(4) if the measured exposure quality does not satisfy the exposure quality threshold (EQT) parameters, then calculating a new set of SCPs and setting said SCPR flag to said second value, indicating that said digital image capture and processing system should be reconfigured prior to acquiring a digital image during the next image acquisition cycle in said system;

otherwise, maintaining said digital image capture and processing system using the current set of SCPs;

(5) if reading a bar code symbol in said digital image is required in the application at hand, then said digital image processing subsystem attempting to process said digital image and reading a barcode symbol graphically represented in said digital image;

(6) if said digital image processing subsystem fails to read a barcode symbol in said digital image, or if barcode reading is not required by the application at hand, and said digital image processing subsystem determined that said exposure quality does not satisfy the exposure quality threshold parameters, then said digital image capture and processing system returns to step (1) above;

(7) if said digital image processing subsystem successfully reads a barcode symbol in said digital image, then said input/output subsystem transmitting symbol character data and/or said digital image to a host system; and

(8) if necessary, said input/output subsystem transmitting said digital image to said host system, or storing said digital image in memory aboard said digital image capture and processing system.

2. The method claim 1, wherein said first group of system control parameters are selected from the group consisting of:

(i) a shutter mode parameter, (ii) an electronic gain parameter, (iii) a programmable exposure time parameter, for each block of pixels detected in said image detection array, (iv) an image capture mode parameter, and (v) an image capture control parameter.

3. The method of claim 1, wherein said second group of system control parameters are selected from the group consisting of:

(i) an illumination mode, (ii) an automatic illumination control parameter, and (iii) an illumination field type parameter.

4. The method claim 2, wherein said shutter mode of image sensor parameter is selected from the group consisting of a single frame shutter mode, a rolling shutter mode, and a video mode.

5. The method of claim 3, wherein said illumination mode parameter is selected from the group consisting of OFF, continuously ON, and strobe/flash values.

6. The method of claim 3, wherein said automatic illumination control parameter is selected from the group consisting of ON and OFF values.

7. The method of claim 3, wherein said illumination field type parameter is selected from the group consisting of narrow-area field of illumination, and wide-area field of illumination.

8. The method of claim 3, wherein said image capture mode is selected from the group consisting of narrow-area image capture, and wide-area image capture.

9. The method of claim 3, wherein said image capture control is selected from the group consisting of single frame, video frame.

10. The method of claim 3, wherein said automatic object detection mode is selected from the group consisting of ON and OFF values.

11. The method of claim 1, wherein said exposure quality threshold (EQT) parameters are selected from the group consisting of brightness level and image saturation.

12. The method of claim 1 wherein said system further comprises an automatic object detection subsystem for detecting the presence of the object within said FOV, and generating said triggering event signal in response thereto.

13. The method of claim 1 wherein said system further comprises an manually-actuatable trigger switch for generating said triggering event signal in response to the actuation of said trigger switch.

14. The method of claim 1, wherein said digital image capture and processing system is realized in the form of a hand-supportable digital-imaging based bar code symbol reader.

15. The method of claim 1, wherein said digital image capture and processing system is realized in the form of a presentation-type digital-imaging based bar code symbol reader.

16. The method of claim 1, wherein said digital image capture and processing system is realized in the form of a digital-imaging based bar code symbol reading engine installed within said host system.

17. The method of claim 16, wherein said digital image capture and processing system further comprises

18. A method of dynamically controlling illumination and imaging operations within a digital image capture and processing system, comprising the sequence of steps:

(a) automatically configuring a digital image capture and processing system with a first set of system control parameters;

(b) illuminating and capturing one or more digital images of an object using said digital image capture and processing system;

(c) automatically performing real-time exposure quality analysis on said digital images captured by said digital image capture and processing system; and

(d) based on the results of said exposure quality analysis performed in step (c), automatically reconfiguring said digital image capture and processing system with a second set of system control parameters, that are different from said first set of system control parameters, so as to dynamically control illumination and imaging operations within said digital image capture and processing system.