A method is provided for image processing. The method includes receiving an image dataset having image data for a plurality of images and a group dataset having group information for each image. The method further includes transforming the image dataset into a sparse vector by applying sparse coding and using the group information. The method also includes dividing each of dimensions of the sparse vector into multiple groups with a matrix. The matrix is generated such that the matrix takes on a higher value when samples in a same group from among the multiple groups have same non-zero dimensions above a threshold amount of time and takes on a lower value compared to the higher value when the samples in the same group lack the same non-zero coefficients above the threshold amount of time. The method additionally includes transforming the sparse vector into a summation vector using the multiple groups.