1. A method for segmenting an image comprising pixels, the method comprising: generating a start model comprising a set of model points approximating an outline of an object in an initial image; subsampling the initial image at a first scale to generate a subsampled image; smoothing the subsampled image at a first smoothing level to generate a smoothed image; generating a curvature image by applying a second derivative operator to the smoothed image; locating, for each of the model points in the start model, second derivative local maxima in the curvature image that are orthogonal to a respective model point and within a search region having a first boundary on one side of the start model and a second boundary on an opposite side of the start model; generating a set of contours by growing a contour for each of the second derivative local maxima; shifting the start model to an outer boundary of the contours; and generating a segmentation mask of the object based on the shifted start model.