GB1494357A - Recognition of objects particularly biological materials - Google Patents

Abstract

1494357 Image analysis OBJECT RECOGNITION SYSTEMS Inc 1 Feb 1975 4472/75 Heading G1A [Also in Division G4] To compare an object with a reference the object is scanned in two dimensions to form an analogue video signal representing the object; portions of the signal, each corresponding to at least one line of the scan, are averaged and compared with the reference. The averaging can be done by filtering or otherwise; the comparison is made by digitizing the average values and comparing these with the reference. In Fig. 1 a biological specimen 14 is illuminated by a flying spot scanner 11, and a video signal is produced by detector 16. This signal is amplified at 17, and filtered at 18 to remove the line scanning frequency, and higher frequencies. The filtered signal is displayed on CRT 19, which is synchronized with the line scan. The signal amplitude is digitized at 21, but not more often than once per line, so that the amount of digital data to be handled is kept small. The digitized signal is coded and fed to computer 23 where it is compared with stored results obtained when a reference specimen was examined. In a further embodiment, Fig. 2, (not shown), a conventional camera tube may be used to scan the specimen; the computer can receive its inputs from a printer attached to the converter. The signals to be compared with a known reference each correspond to the average of at least one line of the scan. If the CRT trace in Fig. 1 is used, it is an average because of filter 18 and because the lines are superimposed. If an A/D converter is used, this may be of the kind which digitizes the average value of a signal during the sampling period (here during at least one line), in which case the further averaging of filter 18 is not necessary though preferable. If the A/D converter is of the type which digitizes the value of a signal at the start of the sampling period, the filter is necessary.