A computer-implemented method and system are described for locating fingernails of a person's hand in an image. An approximate location of each fingernail in the image is determined. An approximate location of each of a plurality of digit-shape objects in the image is initialized based on the approximate locations of the fingernails, and initially refined based on respective digit-shape object models and corresponding functions. The approximate location of each fingernail sub-shape is further refined based on a respective fingernail model and its corresponding function.