An image compression method includes obtaining a hidden variable of an input image using a coding network of a deep learning neural network comprising at least one downsampling back projection module including performing downsampling transformation on a first feature map of the input image input to the downsampling back projection module to obtain a second feature map, obtaining a third feature map having a same resolution as a resolution of the first feature map by reconstructing the second feature map, and obtaining a fourth feature map as an optimization result of the second feature map, based on a difference value between the first feature map and the third feature map; and obtaining a bitstream file of a compressed image by performing entropy coding based on the hidden variable obtained based on the fourth feature map of a last downsampling back projection module.