GB1468168A - Image analysis - Google Patents

Abstract

1468168 Pattern recognition systems IMAGE ANALYSING COMPUTERS Ltd 17 June 1974 [20 June 1973 5 Dec 1973] 29237/73 and 56315/73 Heading G4R In a system in which parameters of features of objects to be recognized are determined a signal ACP is derived for each feature. Signal ACP is indicative of the position within the scanned field of a point defined by the intersection of, for example, a notional horizontal line extending from the lowest part of the feature and a vertical line extending from the right-most part of it. The ACP signal is stored during a first frame scan and used during a subsequent frame scan to gate the parameter value to a store for subsequent use in recognition. Other parameters relating to the same feature may be gated out similarly in respective later scans. When the parameters for that feature have all been gated the ACP signal for the next feature is determined and stored and so on. The features may be on a microscope slide and scanned by a c.r.t. The scanner output is limited to provide contrast amplitude pulses to a feature measuring unit and to circuit determining the ACP signal. A cyclic store may be interposed so that the portion of the field containing the feature under consideration may be 'frozen' until all the parameters have been calculated. The determination of the parameters and the ACP signals is as described in the Specification 1,323,556. Should a preliminary measurement of the parameter value indicate that the feature is not of interest the ACP signal is erased and the ACP signal of the next feature determined. The parameters for any one feature are calculated during successive frame scans and may include, for example, area and perimeter length. The selection of the parameters to be calculated is controlled by a circuit which, inter alia, defines a window surrounding the ACP point and which may display this window on a monitor displaying the scanned field. The parameter values gated by the ACP signal pass via a second gate, controlled by the window signal, to a unit which computes the shape factor for the feature in accordance with the values. The shape factor is fed to the recognition unit.