Remote Sensing is the science and art of acquiring information (spectral, spatial, and temporal) about material objects, area, or phenomenon, without coming into physical contact with them ad plays a significant role in feature extraction. In the present paper, implementation of color mapping index method is analyzed to extract features from RSI in spectral domain. Color indexing is applied after fixing the index value to the pixels of selected ROI (Region of Interest) of RSI and there by clustering based on these index values. Color mapping, which is also called tone mapping can be used to apply color transformations on the final image colors of the ROI. The process of color map indexing is a color map approximation approach on RSI for feature extraction includes designing appropriate algorithm, its implementation and discussion on the results of such implementation on ROI.