According to one embodiment, an encoding apparatus includes a first quantizer, a second quantizer, a predictor and a calculator. The first quantizer quantizes an input block to obtain a first quantized block. The second quantizer quantizes a reference pixel to obtain at least one quantized value. The predictor predicts each target pixel in the first quantized block using the at least one quantized value and a quantized value of a pixel that is to be decoded preceding the target pixel in decoding order in the first quantized block to obtain a second quantized block. The calculator calculates a difference between the first quantized block and the second quantized block.