AUTOMATIC DIGITIZING OF THE COLOUR-LAYER OF THEMATIC MAPS

A method for automatic classification and dcscription of the colour-layer of thcrnatic maps is presented. Owing to the type of noisc appcaring in the scanncd imagcs, we find it useful to combine pixel classificatiorl and rastcr-to-vector convcrsion in ordcr to produce acceptable results. l'hc colour value of an arca is dctcrmincd from a sclcctivcly sampled set of pixcls and a set of threshold valucs. I'ossihlc bordcrlines arc produccd by vcctorizing thc linc-network of the imag, and falsc bordcrlincs are rcmovcd by comparing ncighbouring sub-arcas. Experimental results are discussed, and somc tcst maps arc prc-~cntrtl to illustr:ctc thc pcrformancc of the system