Method to detect and recognize an object in an image, and an apparatus and a computer program for it

摘要

A method for detecting and recognizing a traffic signal in an image (110) supplied as input, such that the method comprises a preliminary treatment stage (130), a treatment stage (140) and a subsequent treatment stage ( 150), such that said preliminary treatment stage (130) is configured to prepare the image (110) supplied as input for the treatment stage (140), said treatment stage (140) is configured to locate at least one Candidate traffic signal in the pretreated image, and said subsequent processing stage is configured to reject false detections and assign a value indicating the accuracy for the correct detections, so that the treatment stage comprises: identifying characteristic points in the image supplied as input and treated preliminary; construct a descriptor for each characteristic point, such that said descriptor comprises a description of the environment of each characteristic point; providing a library comprising a hierarchy of a plurality of templates corresponding to a plurality of traffic signals, so that each template for each traffic signal comprises a plurality of sub-templates representing a part of the traffic signal; match the descriptors with the sub-templates of the library or with corresponding descriptors deduced from those sub-templates; combine the sub-templates corresponding to the matching descriptors, in order to form a candidate traffic signal; such that the template for a traffic signal comprises an image of that traffic signal and the sub-templates each constitute a different part of that image; said method comprising, additionally: storing, for each match, a position and a scale of the characteristic point for which a corresponding descriptor has been matched with a sub-template; characterized by computing, for each sub-template, a line on which the center of the traffic signal corresponding to that coincidence may be; If the lines for a combination of matches corresponding to the same traffic signal are cut, store the cut-off point of the lines as a possible center if the sizes proposed for that traffic signal, based on the scales stored for matches in that combination , are next; group, once all the combinations of matches corresponding to the same traffic signal have been found, the possible centers, and combine the subplants corresponding to the grouping of possible centers to form the actual candidate traffic signal.