The present disclosure is directed to data classification. An exemplary computer-enabled method for classifying image data comprises: receiving an input image patch, wherein the input image patch is of a second data domain; providing the input image patch to a preprocessing algorithm to obtain a preprocessed image patch, wherein the preprocessing algorithm is trained to transform data of the second data domain to data of a first data domain; providing the preprocessed image patch to a pre-trained classification algorithm, wherein the pre-trained classification algorithm is trained based on training data of the first data domain; obtaining one or more classification outputs from the pre-trained classification algorithm based on the preprocessed image patch.