| 摘要 |
A system for detecting the contour of an object situated on a surface, the system comprising (a) an image acquisition assembly, wherein there is relative motion between the image acquisition assembly and the object, the image acquisition assembly comprising (1) a line detector, operable for scanning the surface line by line by virtue of the relative motion, wherein each line is scanned during a scan cycle, the line being transverse to the direction of the relative motion, and (2) a light source, operable for emitting light toward the line detector during active periods between idle periods, such that during each of the active periods the light is emitted for at least one cycle synchronized with the scan cycle, allowing the line detector to acquire a first group of at least one lit scan line, and during each of the idle periods lasting for at least another cycle synchronized with the scan cycle, no light is emitted, allowing the line detector to acquire a second group of at least one unlit scan line, wherein the object passes between the line detector and the light source by virtue of the relative motion, and (b) a processor coupled with the image acquisition assembly, the processor receiving and analyzing scan lines acquired by the line detector, wherein for each of the first group of at least one lit scan line and a successive one of the second group of at least one unlit scan line, the processor identifies a token pattern consisting of a lit segment of the first group adjoining an unlit segment of the second group, the processor searches along the first group and the successive second group for locations where the token pattern ends or reappears, thereby defining edges of the object, and combining the collection of the defined edges to produce a contour of the object. |
