Patent ID: 7278575

Claim:
A hand-supportable digital imaging-based bar code symbol reading device comprising: a hand-supportable housing; 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 image sensing array for detecting imaged light reflected off the object during illumination operations in a image-capture mode in which substantially all rows of the image sensing array are enabled; an LED-based illumination subsystem for producing a field of wide-area narrow-band illumination within said FOV during operation of said image formation and detection subsystem in said image-capture mode; an image capturing and buffering subsystem for capturing and buffering a digital image detected by said image formation and detection subsystem; an image-processing based bar code symbol reading subsystem for automatically processing said digital image captured and buffered by said image capturing and buffering subsystem, wherein said processing comprises three stages of processing, starting from the center or middle spot of said digital image of the object, at which the user is presumed to have aimed said device, and progressing in a helical manner around said center spot of said digital image so that said image-processing based bar code symbol reading subsystem can quickly search for, find and read at least one bar code symbol represented therein, wherein the first stage of processing involves searching for and finding regions of interest (ROIs), possibly containing bar code elements, in said digital image, wherein a low resolution digital image is first derived from said captured digital image using sampling techniques, and then partitioning said low-resolution digital image into blocks of digital image data, including a middle block corresponding to said middle spot of said digital image, and creating a feature vector for the middle block using spatial-derivative based image processing techniques, wherein the second stage of processing involves marking ROIs by examining the feature vectors for regions of high-modulation, and returning to said first stage of processing to create feature vectors for other blocks of image data surrounding the middle block, in a helical manner, calculating the orientation of bar code elements, and eventually marking the four corners of a bar code symbol as a ROI, and wherein the third stage of processing involves reading any bar code symbols represented within the ROI by traversing the bar code symbol and updating the feature vectors, examining the zero-crossings of filtered digital images, creating bar and space patterns, and decoding the bar and space patterns to read one or more bar code symbols; an input/output subsystem for outputting processed image data to an external host system or other information receiving or responding device; and a system control subsystem for controlling or coordinating said subsystems in said hand-supportable digital imaging-based bar code symbol reading device.