GB1563481A - Information signal processing systems - Google Patents

Description

(54) INFORMATION SIGNAL PROCESSING SYSTEMS (71) We, HAJIME INDUSTRIES, LTD., a Japanese Company, of 5-9, Kudanminami 2-chome, Chiyoda-ku, Tokyo, Japan, do hereby declare the invention, for which we pray that a patent may be granted to us, and the method by which it is to be performed, to be particularly described in and by the following statement: This invention relates to information signal processing systems for use with pattern recognition systems.

According to known pattern recognition system, a picture, pattern or the like is divided into, for example, 120 horizontal scanning lines by a television camera and then converted to video signals. Then, the video signals are converted into a sampled signal which has 120 digital values for every one horizontal scanning line, whereby a single picture frame has 14,400 digital values. By application of a stroke method or pattern matching method or the like to the sampled signal, the features of the pattern, characters or the like of a single picture frame are extracted to establish recognition thereof.

As a result, with the known pattern recognition systems the number of digital values for a single picture frame is extremely large, so that the construction of the systems is very complex which leads to the disadvantage that a long processing time is inevitable.

In order to alleviate such disadvantage, one could minimize the sampling frequency, which is equal to the number of digital values of one picture. However, in doing so, the resolution ability of patterns, characters, etc. within one picture is reduced, which is undesirable.

As another method of alleviating the disadvantage, the use of band compression methods may be considered, but the reduction ratio thereof is at most about 1:10 and hence such methods are not very practical.

According to the present invention there is provided an information signal processing system for use with a pattern recognition system which has converting means operative to convert information from something to be recognised into an electrical signal by scanning a target of the converting means by means of horizontal and vertical signals, sampling means operative to sample said electrical signal from the converting means, means operative to receive said electrical signal from said converting means and to produce a sampling signal to be supplied to the sampling means to determine its sampling time within one sampling period, and means operative to sequentially compare output signals from said sampling means with reference signals, the information signal processing system comprising means operative to receive said electrical signal from the converting means and to produce a signal which is approximately equal to said electrical signal from the converting means, said means operative to receive said electrical signal from the converting means having filtering characteristics which are selected relative to said sampling time so as to eliminate high frequency components which are not to be sampled at said sampling time, and said means operative to receive said electrical signal from the converting means being connected to supply said signal which is approximately equal to said electrical signal to the sampling means.

An embodiment of the invention described below enables the construction of the pattern recognition system to be simplified and at the same time reduces the processing time for pattern recognition.

The invention will now be further described, by way of example, with reference to the accompanying drawings, in which: Figure 1 is a block diagram showing a pattern recognition system (data recogni- tion system) which employs an information signal processing system embodying this invention; Figure 2 illustrates an example of a pattern which is to be reconised by the recognition system shown in Figure 1; and Figure 3 shows waveform diagrams used for explaining the operation of the system shown in Figure 1.

Tn Figure 1, reference numeral 1 desig nates an information to information signal converter, such as a television camera, which converts information from a picture, pattern or the like to be recognised into an information signal, for example a video signal, by scanning a target thereof by means of horizontal and vertical signals. By means of the television camera 1, a picture P which has, for example, a black circle pattern BP, as shown in Figure 2, is resolved into, for example, 120 horizontal scanning lines and is then formed into video signals. An original video signal So as obtained from the television camera 1 is a composite video signal which contains synchronising signals Ss, as shown in Figure 3A.The original video signal So from the television camera 1 passes through an amplifier 2 and is then fed to an envelope shaping circuit such as a low pass filter 3 which eliminates signal components higher than a certain frequency (for instance 2 kHz to 7 kHz for a conventional scan frequency of 50 Hz to 60 Hz) from the original video signal So and then, as shown in Figure 3B, produces an approximated video signal SA which consists of the envelope of the video signal So shown in Figure 3A. This approximated video signal SA is supplied to a sampling circuit 4 and sampled thereby.The video signal SA is supplied to a sampling circuit signal as produced by the television camera 1 and passed through the amplifier 2 is fed to a synchronous separation circuit 7 which separates the horizontal and vertical synchronising signals from the original video signal So. The synchronising signals from the circuit 7 are fed to a time base generator 8 which generates a sufficient number of sampling pulses Sp (for example seven) to recognise the picture, pattern or the like during every horizontal period, as shown in Figure 3C. The sampling pulses Sp are fed to the sampling circuit 4 to determine its sampling time within one sampling period.

The number of sampling pulses Sp during one horizontal period or one sampling period does not have to be seven, but can be changed in accordance with the complexity of the pattern to be recognised. The output signal from the sampling circuit 4 is fed through a sampling hold circuit 5 to an A-D converter 6 which produces digital-sampled signals corresponding to the approximated signal SA. The digital-sampled signals from the A-D converter 6 are supplied to an electronic computer 9 which is of well known form and which sequentially compares the output signals from the A-D converter 6 with reference signals previously stored therein.

By way of example, the computer 9 may include a ROM 10 which functions as a prooram memory and stores a predetermined program, a processor 11, and a working memory 12 and a library memory 13 which are constituted by a RAM, the library memory storing reference signals.

When the output signals from the A-D converter 6 are supplied to the computer 9, the processor 11 compares each signal from the A-D converter 6 with the reference signal previously stored in the library memory 13 in a working area of the working memory 12 in accordance with the program memorised in the program memory 10 to detect whether or not they are coincident. The above comparison is sequentially achieved for each signal supplied from the A-D converter 6 to the computer 9 in one horizontal period to carry out the pattern recognition.

As is well known, the library memory 13 includes a number of library memory parts in which there have previously been stored reference signals or sampled signals of approximated signals obtained from video signals of various pictures, patterns and so on, so that various pictures, patterns and so on may be recognised, that is, the shapes, size and the like thereof can be recognised.

The upper limit of the pass band of the low pass filter 3 and the sampling frequency of the sampling circuit 4 are not limited to the above exemplary values, but may be freely selected.

It is also possible in the case of scanning a pattern to produce video signals from a scanned locus that comprises concentric circles, a volute, a star shape of any possible shape.

Since in the system described above the low pass filter is supplied with the original information signal and eliminates signal contents of higher frequency than a certain pre-determined frequency, the sampling circuit is supplied with the output of the low pass filter, and the sampled signal approximated to the original information signal is obtained from the sampling circuit, that is the signal to be sampled is an envelope signal, it is possible to reduce the number of samplings and simplify the construction of the pattern recognition system while, at the same time, considerably shortening the pattern recognition processing time.

This invention may be applied to the recognition of visual information (pictures, patterns and so on) as well as the inspection or supervision of systems, etc., where precision recognition of information is not required.

WHAT WE CLAIM IS:- 1. An information signal processing system for use wih a pattern recognition system which has converting means operative to convert information from something to be recoonised into an electrical signal by scanning a target of the converting means

**WARNING** end of DESC field may overlap start of CLMS **.

Claims (4)

**WARNING** start of CLMS field may overlap end of DESC **. nates an information to information signal converter, such as a television camera, which converts information from a picture, pattern or the like to be recognised into an information signal, for example a video signal, by scanning a target thereof by means of horizontal and vertical signals. By means of the television camera 1, a picture P which has, for example, a black circle pattern BP, as shown in Figure 2, is resolved into, for example, 120 horizontal scanning lines and is then formed into video signals. An original video signal So as obtained from the television camera 1 is a composite video signal which contains synchronising signals Ss, as shown in Figure 3A.The original video signal So from the television camera 1 passes through an amplifier 2 and is then fed to an envelope shaping circuit such as a low pass filter 3 which eliminates signal components higher than a certain frequency (for instance 2 kHz to 7 kHz for a conventional scan frequency of 50 Hz to 60 Hz) from the original video signal So and then, as shown in Figure 3B, produces an approximated video signal SA which consists of the envelope of the video signal So shown in Figure 3A. This approximated video signal SA is supplied to a sampling circuit 4 and sampled thereby.The video signal SA is supplied to a sampling circuit signal as produced by the television camera 1 and passed through the amplifier 2 is fed to a synchronous separation circuit 7 which separates the horizontal and vertical synchronising signals from the original video signal So. The synchronising signals from the circuit 7 are fed to a time base generator 8 which generates a sufficient number of sampling pulses Sp (for example seven) to recognise the picture, pattern or the like during every horizontal period, as shown in Figure 3C. The sampling pulses Sp are fed to the sampling circuit 4 to determine its sampling time within one sampling period. The number of sampling pulses Sp during one horizontal period or one sampling period does not have to be seven, but can be changed in accordance with the complexity of the pattern to be recognised. The output signal from the sampling circuit 4 is fed through a sampling hold circuit 5 to an A-D converter 6 which produces digital-sampled signals corresponding to the approximated signal SA. The digital-sampled signals from the A-D converter 6 are supplied to an electronic computer 9 which is of well known form and which sequentially compares the output signals from the A-D converter 6 with reference signals previously stored therein. By way of example, the computer 9 may include a ROM 10 which functions as a prooram memory and stores a predetermined program, a processor 11, and a working memory 12 and a library memory 13 which are constituted by a RAM, the library memory storing reference signals. When the output signals from the A-D converter 6 are supplied to the computer 9, the processor 11 compares each signal from the A-D converter 6 with the reference signal previously stored in the library memory 13 in a working area of the working memory 12 in accordance with the program memorised in the program memory 10 to detect whether or not they are coincident. The above comparison is sequentially achieved for each signal supplied from the A-D converter 6 to the computer 9 in one horizontal period to carry out the pattern recognition. As is well known, the library memory 13 includes a number of library memory parts in which there have previously been stored reference signals or sampled signals of approximated signals obtained from video signals of various pictures, patterns and so on, so that various pictures, patterns and so on may be recognised, that is, the shapes, size and the like thereof can be recognised. The upper limit of the pass band of the low pass filter 3 and the sampling frequency of the sampling circuit 4 are not limited to the above exemplary values, but may be freely selected. It is also possible in the case of scanning a pattern to produce video signals from a scanned locus that comprises concentric circles, a volute, a star shape of any possible shape. Since in the system described above the low pass filter is supplied with the original information signal and eliminates signal contents of higher frequency than a certain pre-determined frequency, the sampling circuit is supplied with the output of the low pass filter, and the sampled signal approximated to the original information signal is obtained from the sampling circuit, that is the signal to be sampled is an envelope signal, it is possible to reduce the number of samplings and simplify the construction of the pattern recognition system while, at the same time, considerably shortening the pattern recognition processing time. This invention may be applied to the recognition of visual information (pictures, patterns and so on) as well as the inspection or supervision of systems, etc., where precision recognition of information is not required. WHAT WE CLAIM IS:-

1. An information signal processing system for use wih a pattern recognition system which has converting means operative to convert information from something to be recoonised into an electrical signal by scanning a target of the converting means

by means of horizontal and vertical signals, sampling means operative to sample said electrical signal from the converting means, means operative to receive said electrical signal from said converting means and to produce a sampling signal to be supplied to the sampling means to determine its sampling time within one sampling period, and means operative to sequentially compare output signals from said sampling means with reference signals, the information signal processing system comprising means operative to receive said electrical signal from the converting means, said means operative to receive said electrical signal from the converting means having filtering characteristics which are selected relative to said sampling time so as to eliminate time, and said means operative to receive said electrical signal from the converting means being connected to supply said signal which is approximately equal to said electrical signal to the sampling means.

2. An information signal processing system as claimed in claim 1, in which said means operative to receive said electrical signal from the converting means comprises a low pass filter.

3. An information signal processing system as claimed in claim 1 or claim 2, in which said means operative to receive said electrical signal from the converting means is arranged so that said signal approximately equal to said electrical signal from the converting means is an envelope signal of said electrical signal from the converting means.

4. An information signal processing system for use with a pattern recognition system, the information signal processing signal being substantially as herein described with reference to the accompanying drawings.