We develop the red relief image maps (RRIMs) to help interpretations of terrain features in Taroko area, Taiwan. The RRIM is produced based on the combination of the terrain openness and the terrain slope. The software for generating RRIM is Generic Mapping Tools (GMT). A digital elevation model (DEM) with a spatial resolution of 40m is used for both terrain openness and terrain slope computations. The purpose of this research is to develop a new visualization method of topographic maps in order to provide users subtle and important terrain information, and further bring contributions to the regions of disaster prevention, soil and water conservation, environmental monitoring, and resource exploration. In this study, 8 test cases for deriving self-developed RRIMs are designed according to the use of the different search radii for terrain openness computations. The result shows that the cases with search radii of 1000m and 1200m are best recommended. In addition, the ridgelines, valley lines and terrain-based subcatchments are more clearly revealed by the self-developed RRIMs than by the traditional contour plots and color mapping.