Method for Detecting and Recognising an Object in an Image, and an Apparatus and a Computer Program Therefor

A non-transitory computer-readable medium having embodied thereon computer executable instructions which, when executed by a computer, causes the computer to prepare an input image, to locate at least one candidate traffic sign in the prepared input image, to reject one or more false detections of the located at least one candidate traffic sign, to attribute a value that indicates an accuracy of one or more correct detections of the at least one located candidate traffic sign, to identify a plurality of feature points in the prepared input image, to construct a descriptor for each of the plurality of feature points, wherein the descriptor includes a description of a vicinity associated with each of the plurality of feature points, to provide a library comprising a hierarchy of a plurality of templates corresponding to a plurality of traffic signs, each one of the plurality of templates corresponding to a specific traffic sign and comprising a plurality of sub-templates that represent a part of the specific traffic sign, wherein each one of the plurality of templates comprises an image of the specific traffic sign to which it corresponds and the plurality of sub-templates each comprise a different part of the image of the specific traffic sign, to match the descriptor constructed for each of the plurality of feature points to the plurality of sub-templates in the library or to at least one of a plurality of corresponding descriptors derived from the plurality of sub-templates, to combine the plurality of sub-templates matched with the descriptor constructed for each of the plurality of feature points to form the at least one candidate traffic sign, to store a location and a scale of each of the plurality of feature points for which a corresponding descriptor has been matched to a sub-template, to compute a line that corresponds to a center of the at least one candidate traffic sign for the descriptor constructed for each of the plurality of feature points and matched to the plurality of sub-templates in the library that correspond to the at least one candidate traffic sign, if it is determined that two or more lines computed for the descriptor constructed for each of the plurality of feature points and matched to the at least one of the plurality of sub-templates in the library that correspond to the at least one candidate traffic sign cross, to store information related to the crossing of the lines as a candidate center of the at least one candidate traffic sign if the scale stored for the matches in said combination, are within a predetermined range, to cluster the stored information related to the crossing of lines as a candidate center to determine possible centers, and to combine the sub-templates corresponding to the cluster of possible centers to form the at least one candidate traffic sign.

An apparatus, comprising:

• one or more processors;
• and
• a memory storing instructions which, when executed by the one or more processors, causes the one or more processors to prepare an input image, to locate at least one candidate traffic sign in the prepared input image, to reject one or more false detections of the located at least one candidate traffic sign, to a value that indicates an accuracy of one or more correct detections of the at least one located candidate traffic sign, to identify a plurality of feature points in the prepared input image, to construct a descriptor for each of the plurality of feature points, wherein the descriptor includes a description of a vicinity associated with each of the plurality of feature points, to provide a library comprising a hierarchy of a plurality of templates corresponding to a plurality of traffic signs, each one of the plurality of templates corresponding to a specific traffic sign and comprising a plurality of sub-templates that represent a part of the specific traffic sign, wherein each one of the plurality of templates comprises an image of the specific traffic sign to which it corresponds and the plurality of sub-templates each comprise a different part of the image of the specific traffic sign, to match the descriptor constructed for each of the plurality of feature points to the plurality of sub-templates in the library or to at least one of a plurality of corresponding descriptors derived from the plurality of sub-templates, to combine the plurality of sub-templates matched with the descriptor constructed for each of the plurality of feature points to form the at least one candidate traffic sign, to store a location and a scale of each of the plurality of feature points for which a corresponding descriptor has been matched to a sub-template, to compute a line that corresponds to a center of the at least one candidate traffic sign for the descriptor constructed for each of the plurality of feature points and matched to the plurality of sub-templates in the library that correspond to the at least one candidate traffic sign, if it is determined that two or more lines computed for the descriptor constructed for each of the plurality of feature points and matched to the at least one of the plurality of sub-templates in the library that correspond to the at least one candidate traffic sign cross, to store information related to the crossing of the lines as a candidate center of the at least one candidate traffic sign if the scale stored for the matches in said combination, are within a predetermined range, to cluster the stored information related to the crossing of lines as a candidate center to determine possible centers, and to combine the sub-templates corresponding to the cluster of possible centers to form the at least one candidate traffic sign.