A method

utilizing the spatial spectrum feature of a aerophoto to extract the geological informations is presented. According to the aerophoto’s features and the purpose of application

we have made the optical spatial filters. On the coherent optical system

one aerophoto film can be separated into three

corresponding to different spatial frequencies respectively. After digital image processing of the separated films

a color synthetic photograph was obtained. This method can be used to process the single high resolution aerophoto

and we can extract the characteristic informations of the rock formation and its small structures from the image. As it has shown in experimental results

this method is of significance in geological explorations.