1. A method of segmenting a tumor region in an image, the method being implemented via execution of computer instructions configured to run at one or more processing modules and configured to be stored at one or more non-transitory memory storage modules, the method comprising: computing a kernel sparse code for each pixel of at least a portion of the image; identifying, using a classifier, each pixel belonging to the tumor region; computing a first intensity kernel matrix using expert-segmented training images; computing a spatial location kernel matrix using the expert-segmented training images; and fusing the first intensity kernel matrix and the spatial location kernel matrix to obtain a first ensemble kernel matrix.