Auto-exposure method using continuous video frames under controlled illumination
First Claim
1. A method of adaptively controlling strobe illumination processes within a digital image capture and processing system supporting an improved level of image acquisition responsiveness, said method comprising the steps of:
- (a) providing a digital image capture and processing system including a housing having a light transmission aperture, and containing an image formation and detection subsystem with an image detection array with a video image capture mode, an illumination subsystem with an illumination array, an automatic illumination control subsystem, an image capturing and buffering subsystem, a digital image processing subsystem, and an input/output subsystem interfaced to a host system;
(b) upon detecting an object in the field of view (FOV) of said image formation and detection subsystem, said illumination subsystem illuminates the object in the FOV at a first strobe illumination energy level, while said image detection array is detecting a first digital image of the illuminated object using a predetermined exposure duration, and then said image capture and buffering subsystem capturing and buffering said first digital image;
(c) said digital image processing subsystem attempting to read one or more code symbols graphically represented in the first digital image, and if successful, then generating symbol character data which is sent to said host system, and returning to step (b); and
if decode processing is not successful, then advancing to step (d);
(d) upon detecting an object in the FOV of said image formation and detection subsystem, said illumination subsystem illuminates the object in said FOV at a second strobe illumination energy level, substantially greater than said first strobe illumination energy level, while said image detection array is detecting a second digital image of the illuminated object using the same predetermined exposure duration, and then said image capture and buffering subsystem capturing and buffering said second digital image; and
(e) said digital image processing subsystem attempting to read one or more code symbols graphically represented in said second digital image, and if successful, then generating symbol character data which is sent to said host system, and returning to step (b), and if decode processing is not successful, then advancing to step (f);
(f) said digital image processing subsystem analyzing both said first and second digital images, and determining a modified exposure time duration, for subsequent video frames, based upon whether both said first and second digital images as analyzed measures too dark, too bright, or one digital image measures too bright while the other digital image measures too dark;
(g) said illumination subsystem illuminating the object in said FOV at the first strobe illumination energy level, while said image detection array is detecting a first subsequent digital image of the illuminated object using said modified predetermined exposure duration, and then said image capture and buffering subsystem capturing and buffering said first subsequent digital image; and
(h) said digital image processing subsystem attempting to read one or more code symbols graphically represented in said first subsequent digital image, and if successful, then generating symbol character data which is sent to said host system, and returning to step (b).
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Abstract
An adaptive strobe illumination control process for use in a digital image capture and processing system. In general, the process involves: (i) illuminating an object in the field of view (FOV) with several different pulses of strobe (i.e. stroboscopic) illumination over a pair of consecutive video image frames; (ii) detecting digital images of the illuminated object over these consecutive image frames; and (iii) decode processing the digital images in an effort to read a code symbol graphically encoded therein. In a first illustrative embodiment, upon failure to read a code symbol graphically encoded in one of the first and second images, these digital images are analyzed in real-time, and based on the results of this real-time image analysis, the exposure time (i.e. photonic integration time interval) is automatically adjusted during subsequent image frames (i.e. image acquisition cycles) according to the principles of the present disclosure. In a second illustrative embodiment, upon failure to read a code symbol graphically encoded in one of the first and second images, these digital images are analyzed in real-time, and based on the results of this real-time image analysis, the energy level of the strobe illumination is automatically adjusted during subsequent image frames (i.e. image acquisition cycles) according to the principles of the present disclosure.
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Citations
13 Claims
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1. A method of adaptively controlling strobe illumination processes within a digital image capture and processing system supporting an improved level of image acquisition responsiveness, said method comprising the steps of:
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(a) providing a digital image capture and processing system including a housing having a light transmission aperture, and containing an image formation and detection subsystem with an image detection array with a video image capture mode, an illumination subsystem with an illumination array, an automatic illumination control subsystem, an image capturing and buffering subsystem, a digital image processing subsystem, and an input/output subsystem interfaced to a host system; (b) upon detecting an object in the field of view (FOV) of said image formation and detection subsystem, said illumination subsystem illuminates the object in the FOV at a first strobe illumination energy level, while said image detection array is detecting a first digital image of the illuminated object using a predetermined exposure duration, and then said image capture and buffering subsystem capturing and buffering said first digital image; (c) said digital image processing subsystem attempting to read one or more code symbols graphically represented in the first digital image, and if successful, then generating symbol character data which is sent to said host system, and returning to step (b); and
if decode processing is not successful, then advancing to step (d);(d) upon detecting an object in the FOV of said image formation and detection subsystem, said illumination subsystem illuminates the object in said FOV at a second strobe illumination energy level, substantially greater than said first strobe illumination energy level, while said image detection array is detecting a second digital image of the illuminated object using the same predetermined exposure duration, and then said image capture and buffering subsystem capturing and buffering said second digital image; and (e) said digital image processing subsystem attempting to read one or more code symbols graphically represented in said second digital image, and if successful, then generating symbol character data which is sent to said host system, and returning to step (b), and if decode processing is not successful, then advancing to step (f); (f) said digital image processing subsystem analyzing both said first and second digital images, and determining a modified exposure time duration, for subsequent video frames, based upon whether both said first and second digital images as analyzed measures too dark, too bright, or one digital image measures too bright while the other digital image measures too dark; (g) said illumination subsystem illuminating the object in said FOV at the first strobe illumination energy level, while said image detection array is detecting a first subsequent digital image of the illuminated object using said modified predetermined exposure duration, and then said image capture and buffering subsystem capturing and buffering said first subsequent digital image; and (h) said digital image processing subsystem attempting to read one or more code symbols graphically represented in said first subsequent digital image, and if successful, then generating symbol character data which is sent to said host system, and returning to step (b). - View Dependent Claims (2, 3, 4, 5, 6)
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7. A method of adaptively controlling strobe illumination processes within a digital image capture and processing system supporting an improved level of image acquisition responsiveness, said method comprising the steps of:
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(a) providing a digital image capture and processing system including a housing having a light transmission aperture, and containing an image formation and detection subsystem with an image detection array with a video image capture mode, an illumination subsystem with an illumination array, an automatic illumination and exposure control subsystem, an image capturing and buffering subsystem, a digital image processing subsystem, and an input/output subsystem interfaced to a host system; (b) said illumination subsystem illuminating the object in the FOV at a first strobe illumination energy level, while said image detection array is detecting a first digital image of the illuminated object using a predetermined exposure duration, and then said image capture and buffering subsystem capturing and buffering said first digital image; (c) said digital image processing subsystem attempting to read one or more code symbols graphically represented in the first digital image, and if successful, then generating symbol character data which is sent to said host system, and returning to step (b); and
if decode processing is not successful, then advancing to step (d);(d) said illumination subsystem illuminates the object in said FOV at a second strobe illumination energy level, substantially greater than said first strobe illumination energy level, while said image detection array detects a second digital image of the illuminated object using the same predetermined exposure duration, and then said image capturing and buffering subsystem captures and buffers said second digital image; and (e) said digital image processing subsystem attempting to read one or more code symbols graphically represented in said second digital image, and if successful, then generating symbol character data which is sent to said host system, and returning to step (b), and if decode processing is not successful, then advancing to step (f); (f) said digital image processing subsystem analyzing said first and second digital images, and determining a modified exposure time duration, for subsequent video frames, based upon whether said first and second digital images as analyzed measures too dark, too bright, or one digital image measures too bright while the other digital image measures too dark; (g) said illumination subsystem illuminating the object in the FOV at a first modified strobe illumination energy level, while said image detection array detects a first subsequent digital image of the illuminated object using the same predetermined exposure duration, and then said image capture and buffering subsystem capturing and buffering said first subsequent digital image; and (h) said digital image processing subsystem attempting to read one or more code symbols graphically represented in said first subsequent digital image, and if successful, then generating symbol character data which is sent to said host system, and returning to step (b). - View Dependent Claims (8, 9, 10, 11, 12, 13)
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Specification