1. An image processing method for denoising of an input image to generate an output image, the method comprising: transforming first image data of a spatial region extracted from the input image in a unit of a predetermined block into second image data of a frequency region including a plurality of frequency components; calculating a per-block activity evaluation value based on the first image data; setting a per-block quantization value based on the per-block activity evaluation value; quantizing the second image data based on the per-block quantization value to generate third image data with noise in the input image removed; and generating the output image based on the third image data.