Abstract: The present invention is a technique for use in image processing for extracting feature information from an array of pixels. Each pixel within the array of pixels has a pixel value selected from among a plurality of possible pixel values. As the pixels are recalled from the array of pixels in a raster scan fashion a pixel address memory is incremented to contain a current pixel address indicative of the location of the current pixel. If the current pixel is the first occurrence of its pixel value, the current pixel address is stored in a first occurrence pointer memory at a memory location corresponding to the current pixel value. The current pixel address is stored within a last occurrence pointer memory at the memory location corresponding to the current pixel value. The current pixel address is stored in a memory location within a linked-list memory corresponding to a pixel address stored within the last occurrence pointer memory at a memory location corresponding to the current pixel address.

Abstract: A system including electronic, mechanical and optical mechanisms which enable the system to: "read" a human fingerprint directly from a human finger; convert the ridge-valley pattern of that fingerprint into an electronic representation; transmit the electronic representation to a centralized location where image processing computing equipment can locate and extract the distinctive characteristics or minutiae of the fingerprint; compare the minutiae with minutiae previously recorded from the fingerprints of persons whom the system is responsible for identifying; determine whether the identity of the person whose fingerprint is read is known, and, if known, whether or not the person is authorized to enter the portal equipped with this system, or to otherwise act; and, to transmit a signal to the terminal and/or portal regarding the system's decision.

Abstract: A pattern recognition apparatus for recognizing or identifying fingerprint images and the like is described. The apparatus enables the determination of the coordinates and angular positions of characteritic points such as fingerprint minutiae. The pattern recognition apparatus includes a high resolution scanner for scanning a fingerprint impression or image, an analog to digital converter to convert the scanner signals to a digitally encoded image having many levels of gray scale data, an image enhancer to eliminate imperfections in the imagery, pre-editing circuits to edit out areas of the image which should not be further processed, a minutiae detection system having high redundancy to reduce the probability of missed minutiae, and a post-editing subsystem to eliminate false minutiae detections.