Object detection in an image using an image processing approach in which the image is updated based on an energy function. In one aspect, the exemplary image update process attempts to homogenize each region by associating each pixel with a particular region such that the total level of energy for the image based on the pixel located in that region is minimized with respect to the energy function. For example, the method of object detection in an image having a plurality of pixels by image segmentation includes dividing the image into a plurality of regions; assigning each pixel to one of the plurality of regions based on a characteristic; performing an energy reduction on the image based on a region reassignment of at least one pixel; and producing an output image based on the energy reduction.