The present disclosure provides an image encoding method and apparatus and an image decoding method and apparatus for generating a reconstructed image having a minimized error between an original image and the reconstructed image at a high bit depth and a high bit rate.The image decoding method includes parsing offset values and an offset type from a bitstream; parsing a class based on the offset type from the bitstream; selecting a plurality of pixels from among pixels adjacent to a reconstructed pixel, based on the class, and calculating a reference value based on sample values of the plurality of pixels; determining a category based on a magnitude of a difference value between the reference value and a sample value of the reconstructed pixel; selecting an offset value from among the offset values, the offset value corresponding to the category; and compensating for the sample value of the reconstructed pixel by using the selected offset value.