A system, medium, and method providing a thumbnail visualizing a plurality of features representing an event to facilitate a search of images. In the system, medium, and method, photographs may be classified into groups based on metadata, e.g., embedded in a photograph file, and a thumbnail may be generated by combining object images extracted from individual representative photographs of the respective groups. The generation of the thumbnail may include extracting metadata from photograph files stored in a photograph folder, classifying the photograph files into groups based on the metadata, selecting representative photographs from the groups using color information included in the metadata, and combining object images extracted from the representative photographs into a thumbnail.