An image processing device according to one embodiment includes a processor. The processor executes a step of acquiring an input image, a step of calculating a feature residual by processing the input image in a convolutional layer, a step of performing at least one convolution on the input image, a step of generating an output feature by applying the feature residual to the convolved input image, and a step of generating an image residual based on the output feature. The image residual is applied to the input image, and thereby a high-resolution image with higher resolution than the input image is generated.