US3602887A
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Pattern classification method and apparatus
Assignee: International Business Machines Corp
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Filing: 1968-02-09
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Granted: 1971-08-31
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Expires: 1988-02-09
Abstract
Abstract The apparatus for practicing the method of classifying patterns is a character recognition system. An optical representation of a function of an unknown character is obtained by applying noncoherent light to a document on which the character is recorded. This optical representation is then applied to a number of masks, one for each possible character, which contain optical representation of the characters, and an optical correlation function for each mask is produced. Each of these optical correlation functions is applied to a separate group of photocells, which produce signals that are linearly proportional to the intensity of different portions of the correlation function. The output of each photocell is applied to a nonlinear diode which produces an output proportional to a constant raised to the value represented by the input signal applied to the diode. The outputs from these diodes for each correlation function are summed to provide a signal representative of a nonlinear function of each correlation function. Since the outputs from all photocells in a given group are summed, it makes no difference which photocell emits the peak representing output and thus the positional registrations is immaterial. This makes the system translation invariant. The representative signals are compared in a maximum selection circuit to determine which signal is largest and thus identifies the unknown character. The invention is also embodied in a system in which coherent light supplied by a laser is applied to the unknown character to obtain a coherent light representation of that character. In this system, the masks storing the optical functions of the unknown characters are in the form of a hologram. Further, field effect transistors are connected to the outputs of the photocells. These transistors translate the outputs of the photocells, which are representative of the intensity of the applied light, to outputs which are proportional to the square root of the intensity of applied light, and these outputs are applied as inputs to the nonlinear or exponential diodes.
Inventors
- 👤 Chao K Chow
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-24 22:17
CPC Classifications
G; G06; G06V; G06V10/00; G06V10/88
Claims Analysis
Total Claims: 12
Claim 1
Independent Claim
192 words
In a method of classifying patterns of the type in which a coherent light representation of an unknown pattern to be classified is correlated with each of a plurality of holographic stored representations of known patterns to obtain in optical form, by application of coherent light, for each such correlation, a correlation function, the improvement comprising the steps of: a. applying each optical correlation function to a plurality of essentially linearly responsive photoresponsive devices to obtain, for each correlation function, a plurality of discrete electrical signals each having a value representative of a portion of said correlation function; b. applying each said electrical signal to a square root circuit to produce a corresponding output electrical signal proportional to the square root of the input signal; c. applying each last said electrical signal to an exponential circuit to producE an electrical output proportional to a constant raised to a power equal to the value of said last said signal; d. for each correlation function summing the outputs from corresponding said exponential circuit; and e. comparing the summed outputs for the plurality of correlation functions to determine the proper classification for said unknown pattern.
Claim 2
Dependent Claim
192 words
In a method of classifying patterns of the type in which a coherent light representation of an unknown pattern to be classified is correlated with each of a plurality of holographic stored representations of known patterns to obtain in optical form, by application of coherent light, for each such correlation, a correlation function, the improvement comprising the steps of: a. applying each optical correlation function to a plurality of essentially linearly responsive photoresponsive devices to obtain, for each correlation function, a plurality of discrete electrical signals each having a value representative of a portion of said correlation function; b. applying each said electrical signal to a square root circuit to produce a corresponding output electrical signal proportional to the square root of the input signal; c. applying each last said electrical signal to an exponential circuit to producE an electrical output proportional to a constant raised to a power equal to the value of said last said signal; d. for each correlation function summing the outputs from corresponding said exponential circuit; and e. comparing the summed outputs for the plurality of correlation functions to determine the proper classification for said unknown pattern.
Claim 3
Independent Claim
202 words
The method of recognizing characters comprising the steps of: a. obtaining an optical representation of an unknown character to be recognized by applying coherent light to the character; b. applying said optical representation to a plurality of representations of known characters stored in holographic form to provide optical correlation functions of said unknown character representation with each of said stored character representations; c. converting each said optical correlation function to a plurality of first electrical signals proportional to the intensity of the light in various portions of said correlation function; d. for each said plurality of said first electrical signals deriving a corresponding plurality of second electrical signals proportional, signal for signal, to the square root of said first signals; e. converting each said second electrical signal of each said plurality of second signals to a corresponding third electrical signal proportional to a constant raised to a power equal to the value of said second electrical signal being converted; f. summing said corresponding third signals of each said plurality to provide one signal for each correlation function; and g. comparing last said signals for said correlation functions to determine which of said stored characters is the best match for said unknown character.
Claim 4
Independent Claim
202 words
The method of recognizing characters comprising the steps of: a. obtaining an optical representation of an unknown character to be recognized by applying coherent light to the character; b. applying said optical representation to a plurality of representations of known characters stored in holographic form to provide optical correlation functions of said unknown character representation with each of said stored character representations; c. converting each said optical correlation function to a plurality of first electrical signals proportional to the intensity of the light in various portions of said correlation function; d. for each said plurality of said first electrical signals deriving a corresponding plurality of second electrical signals proportional, signal for signal, to the square root of said first signals; e. converting each said second electrical signal of each said plurality of second signals to a corresponding third electrical signal proportional to a constant raised to a power equal to the value of said second electrical signal being converted; f. summing said corresponding third signals of each said plurality to provide one signal for each correlation function; and g. comparing last said signals for said correlation functions to determine which of said stored characters is the best match for said unknown character.
Claim 5
Independent Claim
204 words
The method of recognizing characters comprising the steps of: a. obtaining an optical representation of an unknown character to be recognized by applying coherent light to the character; b. applying said optical representation to a plurality of representations of known characters stored in holographic form to provide optical correlation functions of said unknown character representation with each of said stored character representations; c. converting each said optical correlation function to a plurality of first electrical signals proportional to the square of the amplitude of the light in various portions of said correlation function; d. for each said plurality of said first electrical signals deriving a corresponding plurality of second electrical signals proportional, signal for signal, to the square root of said first signals; e. converting each said second electrical signal of each said plurality of second signals into a corresponding third electrical signal proportional to a constant raised to a power equal to the value of said second electrical signal being converted; f. summing said corresponding signals of each said plurality to provide one signal for each correlation function; and g. comparing last said signals for said correlation functions to determine which of said stored characters is the best match for said unknown character.
Claim 6
Independent Claim
204 words
The method of recognizing characters comprising the steps of: a. obtaining an optical representation of an unknown character to be recognized by applying coherent light to the character; b. applying said optical representation to a plurality of representations of known characters stored in holographic form to provide optical correlation functions of said unknown character representation with each of said stored character representations; c. converting each said optical correlation function to a plurality of first electrical signals proportional to the square of the amplitude of the light in various portions of said correlation function; d. for each said plurality of said first electrical signals deriving a corresponding plurality of second electrical signals proportional, signal for signal, to the square root of said first signals; e. converting each said second electrical signal of each said plurality of second signals into a corresponding third electrical signal proportional to a constant raised to a power equal to the value of said second electrical signal being converted; f. summing said corresponding signals of each said plurality to provide one signal for each correlation function; and g. comparing last said signals for said correlation functions to determine which of said stored characters is the best match for said unknown character.
Claim 7
Dependent Claim
260 words
A pattern classification apparatus of the type which includes means for providing an optical representation of an unknown pattern, which is applied to means storing representations of a plurality of known patterns to provide optical correlation functions of said unknown pattern representation with each of said known pattern representations, and means to which said optical correlation functions are applied to classify said unknown pattern, the improvement being that said means to which said optical correlation functions are applied include: a. a plurality of groups of photoresponsive devices, one group for each known representation, each said device being responsive to produce an electrical output representative of a different portion of the applied optical correlation function; b. a plurality of groups of square root circuit devices each deviCe being coupled to receive as an input signal the electrical output of a corresponding said photoresponsive device to produce an electrical output signal proportional to the square root of said input signal; c. a plurality of groups of exponential devices each device being coupled to receive as an input signal the electrical output of a corresponding said square root device to produce an electrical signal proportional to a constant raised to a power proportional to said input signal; d. a plurality of summing circuits, one for each said known representation, each being coupled to receive and sum all electrical outputs from a corresponding said group of exponential devices; and e. comparing circuitry coupled to receive the summed outputs of all said summing circuits and operative to indicate which of the summed outputs is largest.
Claim 8
Dependent Claim
260 words
A pattern classification apparatus of the type which includes means for providing an optical representation of an unknown pattern, which is applied to means storing representations of a plurality of known patterns to provide optical correlation functions of said unknown pattern representation with each of said known pattern representations, and means to which said optical correlation functions are applied to classify said unknown pattern, the improvement being that said means to which said optical correlation functions are applied include: a. a plurality of groups of photoresponsive devices, one group for each known representation, each said device being responsive to produce an electrical output representative of a different portion of the applied optical correlation function; b. a plurality of groups of square root circuit devices each deviCe being coupled to receive as an input signal the electrical output of a corresponding said photoresponsive device to produce an electrical output signal proportional to the square root of said input signal; c. a plurality of groups of exponential devices each device being coupled to receive as an input signal the electrical output of a corresponding said square root device to produce an electrical signal proportional to a constant raised to a power proportional to said input signal; d. a plurality of summing circuits, one for each said known representation, each being coupled to receive and sum all electrical outputs from a corresponding said group of exponential devices; and e. comparing circuitry coupled to receive the summed outputs of all said summing circuits and operative to indicate which of the summed outputs is largest.
Claim 9
Dependent Claim
37 words
The apparatus of claim 4 wherein each of the photoresponsive devices is a linearly responsive device, each of said square root devices is a field effect transistor, and each of said exponential devices is a nonlinear diode.
Claim 10
Dependent Claim
35 words
The apparatus of claim 4 wherein said optical representation of said unknown pattern is provided by applying coherent light to said pattern and said mask means store holographic representation of said plurality of known patterns.
Claim 11
Dependent Claim
205 words
A pattern classification apparatus of the type which includes means for providing an optical representation of an unknown pattern by applying coherent light to said pattern, which representation is applied to means storing holographic representations of a plurality of known patterns to provide an optical correlation function of said unknown pattern representation with each of said known pattern representations, and means to which said optical correlation functions are applied to classify said unknown pattern, the improvement being that said means to which said optical correlation functions are applied include: a. a plurality of photoresponsive devices each responsive to produce an electrical output linearly proportional to the light intensity of a different portion of the applied optical correlation function; b. a plurality of field effect transistors each being connected to receive and operative to convert said electrical output of a corresponding said photoresponsive device to a signal having a value equal to the square root of the value of said output signal; and c. a plurality of nonlinear diodes each having its input coupled to a corresponding one of said field effect transistors and its output connected to circuitry for analyzing the electrical outputs of these diodes to determine the proper classification of the unknown pattern.
Claim 12
Dependent Claim
205 words
A pattern classification apparatus of the type which includes means for providing an optical representation of an unknown pattern by applying coherent light to said pattern, which representation is applied to means storing holographic representations of a plurality of known patterns to provide an optical correlation function of said unknown pattern representation with each of said known pattern representations, and means to which said optical correlation functions are applied to classify said unknown pattern, the improvement being that said means to which said optical correlation functions are applied include: a. a plurality of photoresponsive devices each responsive to produce an electrical output linearly proportional to the light intensity of a different portion of the applied optical correlation function; b. a plurality of field effect transistors each being connected to receive and operative to convert said electrical output of a corresponding said photoresponsive device to a signal having a value equal to the square root of the value of said output signal; and c. a plurality of nonlinear diodes each having its input coupled to a corresponding one of said field effect transistors and its output connected to circuitry for analyzing the electrical outputs of these diodes to determine the proper classification of the unknown pattern.
References Cited (Backward Citations)
No citation records indexed.
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1974-08-30 | 1975-03-01 | 1975-08-31 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1978-08-30 | 1979-03-01 | 1979-08-31 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1982-08-30 | 1983-03-01 | 1983-08-31 | $7700.00 | Window Closed / Lapsed |