Abstract: A gamma camera includes a detector array of a plurality of detector pixels. Each detector pixel is configured to generate a signal indicative of gamma or x-ray radiation incident on that detector pixel. Each collimator of a collimator array is configured to collimate the radiation onto a detector pixel. An actuator is configured to move the collimator array along an axis in one or a plurality of incremental movements, each incremental movement smaller than a lateral dimension of a detector pixel along that axis. A processor is configured to obtain the signals generated by each detector pixel of the plurality of detector pixels and to generate image data with sub-pixel resolution from the sampled signals and a position of the collimator when each signal was generated.