An apparatus for identifying a candidate object in image data and determining a likelihood that the candidate object is an object from an object class, the apparatus comprising: an image data receiving unit for receiving image data of an object of the object class, wherein the image data comprise image elements representing a physical property value of the image data, a seed element selecting unit for selecting a portion of the image elements as seed elements, and a contour point identifying unit for identifying, for each seed element, contour points, the contour points of a seed element circumscribing a candidate object which comprises the seed element, characterized in that the apparatus further comprises: a seed score determining unit for determining, for each seed element, a seed score indicative of a likelihood that the candidate object is an object from the object class, the seed score determining unit comprising: a contour point subset generating unit for generating, for each seed element, a plurality of contour point subsets of the contour points of the seed element, an arc segment generating unit for generating, for each seed element, a fitted arc segment for each of the contour point subsets of the seed element by fitting an arc segment to each of the contour point subsets of the seed element, a fitted arc segment selecting unit for selecting, for each seed element, those fitted arc segments that fulfill a predetermined selection criterion, and a seed score assigning unit for assigning, to each seed element, the seed score based on the selected arc segments. an image data receiving unit for receiving image data of an object of the object class, wherein the image data comprise image elements representing a physical property value of the image data, a seed element selecting unit for selecting a portion of the image elements as seed elements, and a contour point identifying unit for identifying, for each seed element, contour points, the contour points of a seed element circumscribing a candidate object which comprises the seed element, characterized in that the apparatus further comprises: a seed score determining unit for determining, for each seed element, a seed score indicative of a likelihood that the candidate object is an object from the object class, the seed score determining unit comprising: a contour point subset generating unit for generating, for each seed element, a plurality of contour point subsets of the contour points of the seed element, an arc segment generating unit for generating, for each seed element, a fitted arc segment for each of the contour point subsets of the seed element by fitting an arc segment to each of the contour point subsets of the seed element, a fitted arc segment selecting unit for selecting, for each seed element, those fitted arc segments that fulfill a predetermined selection criterion, and a seed score assigning unit for assigning, to each seed element, the seed score based on the selected arc segments. a seed score determining unit for determining, for each seed element, a seed score indicative of a likelihood that the candidate object is an object from the object class, the seed score determining unit comprising: a contour point subset generating unit for generating, for each seed element, a plurality of contour point subsets of the contour points of the seed element, an arc segment generating unit for generating, for each seed element, a fitted arc segment for each of the contour point subsets of the seed element by fitting an arc segment to each of the contour point subsets of the seed element, a fitted arc segment selecting unit for selecting, for each seed element, those fitted arc segments that fulfill a predetermined selection criterion, and a seed score assigning unit for assigning, to each seed element, the seed score based on the selected arc segments. a contour point subset generating unit for generating, for each seed element, a plurality of contour point subsets of the contour points of the seed element, an arc segment generating unit for generating, for each seed element, a fitted arc segment for each of the contour point subsets of the seed element by fitting an arc segment to each of the contour point subsets of the seed element, a fitted arc segment selecting unit for selecting, for each seed element, those fitted arc segments that fulfill a predetermined selection criterion, and a seed score assigning unit for assigning, to each seed element, the seed score based on the selected arc segments.