Computer processing for extracting thematic information has been deve- loped by using different band ratio of TM data. In the course of the researchesauthors advanced two new methods

Directional Transformation method and LogicalIntersection method. In southern areas of subtropical volcanic rock covered with vegetation such asXin Chang

Ba Mao and Xi Kou area

the satisfied effects have been obtained.Thenew methods can eliminate the interfering information of vegetation and other ob-jects

and the hydrothermal alteration information can be extracted effectively.Itsimportance is to explore Au

Ag and multiple metalliferous ore. In the aspect of extracting information about oil gas show and detecting oilfield with the information directly in area of southern red basin

a good resulthas been achieved too by using the new method of Logical Intersection. It shows that the new methods posed in this paper is practical and have wideapplied prospects.