An image processor includes memory and circuitry. The circuitry performs processing of approximating a decompressed image to an original image by using a neural network model trained to approximate the decompressed image to the original image. The decompressed image is obtained as a result of compression of the original image and decompression of the compressed image. The neural network model includes one or more convolutional blocks, and includes one or more residual blocks. Each of the one or more convolutional blocks is a processing block including a convolutional layer. Each of the one or more residual blocks includes a convolutional group including at least one of the one or more convolutional blocks, inputs data which is input to the residual block to the convolutional group included in the residual block, and adds the data input to the residual block to data to be output from the convolutional group.