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; performing quantization on the second image data to generate third image data; calculating a per-block activity evaluation value based on the first image data; and setting a per-block quantization value for quantization based on the per-block activity evaluation value.