Image binarization is one of the key steps in scanning digitizing of mining maps. Binarization result directly affects the efficiency and precision of consequent vector reconstruction. After the analysis of various kinds of image binarization algorithms in the processing of scanned mining maps

we bring forward a new image binarization method based on set operation of binary images

which is named as Dynamic Adaptive Binarization with Multi Thresholds. This approach can take into account the gray levels of the whole frame and the neighborhood feature of the pixels simultaneously. With this method

Image binarization is easy and fast

and it can get rid of adhesion and rupture of the lines in the scanned maps.