A computer-implemented method for assigning attributes to an image. The method comprises allowing a user to mark a plurality of pixels of an image as a single marked area by a single scribble, the single marked area defines, for a current iteration, a target attribute, determining according to the target attribute an optimal function that defines at least one respective attribute of pixels in the image, assigning the at least one respective attribute to pixels in the image according to the optimal function, and displaying the at least one attribute of the pixels.