Patent attributes
An attachable matter detection apparatus includes a controller configured to function as an extractor and a detector. The extractor extracts edge information of each pixel contained in a photographic image photographed by an imaging device. The detector detects a candidate area estimated to have a water droplet out of the photographic image based on a matching result between (i) each of the pixels converted into a predetermined data format based on the edge information extracted by the extractor and (ii) a template representing a water droplet and having the data format. The detector calculates a matching frequency with the template for a predetermined area along a contour of the candidate area, and excludes the candidate area when the candidate area satisfies a predetermined exclusion condition based on the matching frequency.
