Abstract: A microfilm reader, which includes a bar code scanner, a controller, and a keyboard, receives microfilm containing documents and corresponding bar code symbols. Each bar code symbol contains data describing the contents of a respective document. The bar code scanner reads the bar code symbols located on the microfilm and transmits data representing the read bar code symbols to the controller. The controller determines whether the data received from the bar code scanner satisfies search criteria entered into the keyboard.

Abstract: A nonvolatile electro-optical read-only memory includes a substrate on which is printed (or otherwise inscribed) a complex symbol or "label" with a high density two-dimensional symbology, a variable number of component symbols or "codewords" per row, and a variable number of rows. Codewords in alternating rows are selected from mutually exclusive subsets of a mark pattern such as a (17,4) mark pattern. The subsets are defined in terms of particular values or a discriminator function, which is illustrated as being a function of the widths of bars and spaces in a given codeword. In the illustrated embodiment, each subset includes 929 available codewords; that, plus a two-step method of decoding scanned data, permitting significant flexibility in defining mappings of human-readable symbol sets into codewords. The memory may be used in conjunction with a scanner and a suitable control system in a number of applications, e.g., robotic operations or automated microfilm searching.

Abstract: A method for decoding an analog waveform corresponding to a symbol comprises detecting the extrema locations of the waveform, and creating a feature vector from these extrema locations. The feature vector is compared to stored reference arrays corresponding to each symbol from an alphabet of possible symbols using statistical pattern recognition techniques to decode the waveform. The invention also features an analog waveform decoder that has reference storage for holding reference arrays, and a processor that creates and decodes a feature vector for the analog waveform.

Abstract: A nonvolatile electro-optical read-only memory includes a substrate on which is printed (or otherwise inscribed) a complex symbol or "label" with a high density two-dimensional symbology, a variable number of component symbols or "codewords" per row, and a variable number of rows. Codewords in alternating rows are selected from mutually exclusive subsets of a mark pattern such as a (17,4) mark pattern. The subsets are defined in terms of particular values of a discriminator function, which is illustrated as being a function of the widths of bars and spaces in a given codeword. In the illustrated embodiment, each subset includes 929 available codewords; that, plus a two-step method of decoding scanned data, permitting significant flexibility in defining mappings of human-readable symbol sets into codewords. The memory may be used in conjunction with a scanner and a suitable control system in a number of applications, e.g., robotic operations or automated microfilm searching.

Abstract: A method for decoding information contained in an analog waveform representative of a bar code symbol comprising the steps of identifying a decodable portion of an analog waveform; processing said decodable portion to obtain a plurality of waveform descriptors; and performing a high and low density decoding process to one or more of said plurality of waveform descriptors for decoding information contained in either a high or low density symbol respectively, is disclosed. The high density decoder used for decoding high density symbols utilizes extrema extents, i.e., areas of the peaks and valleys of the analog waveform which directly correlate to the size of the bars/spaces of a high density bar code. After locating the seed point of the waveform, each extrema extent is generated and thresholded at each peak/valley location to decide its size. The high density decoder is adaptive in that the thresholding extent value is updated as the solution grows away from the seed point.

Abstract: A nonvolatile electro-optical read-only memory includes a substrate on which is printed (or otherwise inscribed) a complex symbol or "label" with a high density two-dimensional symbology, a variable number of component symbols or "codewords" per row, and a variable number of rows. Codewords in alternating rows are selected from mutually exclusive subsets of a mark pattern such as a (17,4) mark pattern. The subsets are defined in terms of particular values of a discriminator function, which is illustrated as being a function of the widths of bars and spaces in a given codeword. In the illustrated embodiment, each subset includes 929 available codewords; that, plus a two-step method of decoding scanned data, permitting significant flexibility in defining mappings of human-readable symbol sets into codewords. The memory may be used in conjunction with a scanner and a suitable control system in a number of applications, e.g., robotic operations or automated microfilm searching.

Abstract: A method and an apparatus which scans and recognizes a page having columns of text or pictorial images. The scanned page is partitioned into blocks of scanlines and the column gap between the columns are identified by a projection profile process. With this technique the page can be severely tilted while under scan and still be properly recognized.

Abstract: A method for decoding bar code symbols in which a bar code reader and associated components scan a bar code symbol, produce a representation of the symbol, and attempt to decode that representation in order to produce a character message. The method consists of the steps of storing a first representation of the bar code symbol corresponding to a first scan path through a first portion of said symbol smaller than the entire symbol, and storing a second representation of the bar code symbol corresponding to a second scan path through the symbol. The method then processes said representations in the event a successful decode has not taken place by utilizing the signal from a first scan with the signal from a subsequent scan to determine the best alignment at which successive scans can be concatenated to form a combined signal. The process is repeated with different subsequent scans until successful decoding of the combined signal.

Abstract: A method for reading bar code symbols which enables legitimate characters recognized by the code in use to be derived from a plurality of scans corresponding to illegitimate characters not recognized by the code in use is disclosed. The method includes the steps of storing representations of the bar code symbol which cannot be decoded to produce legitimate character(s). One of the representations is improved, or corrected, using another representation, and an attempt is made at decoding the corrected representation to produce a legitimate character. If the decoding attempt is not successful, further corrections are made in order to provide a representation which may be decoded to produce a legitimate character.

Abstract: A method for decoding bar code symbols in which a bar code reader and associated components scan a bar code symbol produce a representation of the symbol, and attempt to decode that representation in order to produce a character message. The method consists of the steps of storing a first representation of the bar code symbol corresponding to a first scan path through a first portion of said symbol smaller than the entire symbol, and storing a second representation of the bar code symbol corresponding to a second scan path through the symbol. The method then processes these representations in the event a successful decode has not taken place by utilizing the signal from a first scan with the signal from a subsequent scan to determine whether the information from successive scans can be concatenated to form a combined signal. The process is repeated with different subsequent scans until successful decoding of the combined signal.