A data storage management system incorporates image recognition and classification features. The illustrative system generates thumbnail images to represent images detected in secondary copies. Subsequent image recognition and classification operations are based on the thumbnail images without need to access the secondary copies from which the thumbnails were derived. The system indexes thumbnail images and respective relationships to each other and to the source secondary copies. Metadata from the source secondary copies is extracted and preserved with the thumbnails. Thumbnail images, metadata, and related index data (collectively “thumbnail data”) are stored locally in an illustrative content index server, or in an enhanced storage manager, thus improving performance without interfering with ongoing storage management operations. Features are disclosed for searching within the system and performing storage management operations based on image criteria. Access to/from other systems is also possible, e.g., for importing images and/or thumbnails.