Alpha channel post processing in image coding can include decoding, from multiple color channels of a bitstream, color channel values for an encoded image, decoding, from an alpha channel of the bitstream, alpha channel values for the encoded image, determining a bilateral filter based on a level of compression for encoding the alpha channel, post processing the alpha channel values by filtering the alpha channel values using the bilateral filter to obtain filtered alpha channel values, and generating at least a portion of a reconstructed image corresponding to the encoded image using the filtered alpha channel values and the color channel values.