A processing device is provided which includes memory and a processor. The processor is configured to receive an input image having a first resolution, generate at least one linear down-sampled version of the input image via a linear upscaling network, generate at least one non-linear down-sampled version of the input image via a non-linear upscaling network, extract a first feature map from the at least one linear down-sampled version of the input image, and extract a second feature map from the at least one non-linear down-sampled version of the input image. The processor is also configured to convert the at least one linear down-sampled version of the input image and the at least one non-linear down-sampled version of the input image into pixels of an output image having a second resolution higher than the first resolution using the first feature map and the second feature map.