There is provided an encoding apparatus, an encoding method, a decoding apparatus, and a decoding method that make it possible to improve the performance of a filter process. The encoding apparatus and the decoding apparatus perform classification of classifying, according to a reliability degree determined according to a frequency distribution of inclination directions indicating directions of inclination of pixel values of a plurality of pixels in a frequency distribution generation region including a pixel of interest of a decoded image, the pixel of interest into any of a plurality of classes, and performs a filter process of applying, to the decoded image, a prediction formula for performing product sum calculation of tap coefficients of the class of the pixel of interest obtained by the classification and pixels of the decoded image. The present technology can be applied, for example, to a case in which encoding and decoding of an image are performed.