Method and apparatus for dynamic thresholding of grayscale images to delineate image attributes

摘要

A method and apparatus for dynamic thresholding of grayscale images to delineate image attributes is disclosed. The system includes a picker assembly, an imager disposed on picker assembly, illumination sources disposed at the picker assembly and a processor, coupled to the imager and illumination sources, for processing image data obtained from the imager and for controlling the illumination sources, wherein the processor applies dynamic image thresholding to the image to select an optimum gray scale level of the image, the image expected to include a desired physical feature. The processor performs dynamic image thresholding by identifying a region of interest around the area where the intersection is expected to be, thresholding the portion of the image within the region of interest with an experimental value, calculating the ratio of black pixels to the total number of pixels, using a search method that is based on a histogram of the ratio across the threshold spectrum to actively search for a threshold value that produces a closest match to the target ratio value and thresholding the entire image with the threshold value producing the closest match to the target value.