Coding method, coding apparatus, decoding method and decoding apparatus using subsampling

A coding apparatus includes: a context generator generating a context signal from a reconstructed symbol; a predictor generating a prediction signal indicating a prediction value which is a prediction of a symbol to be coded, based on the context signal, and a prediction error signal which is a difference between the prediction value and the symbol; a quantizer generating a quantized prediction error signal by quantizing the prediction error signal; an encoder coding the quantized prediction error signal by referring to the context signal; an inverse quantizer subjecting the quantized prediction error signal to inverse quantization so as to generate a reconstructed prediction error signal; an inverse predictor subjecting the reconstructed prediction error signal to inverse prediction so as to generate a reconstructed sampled signal; a subsampling control circuit generating a subsampling control signal indicating whether or not the symbol should be subject to subsampling; and an interpolator referring to the subsampling control signal so as to subject to interpolation the reconstructed sampled signal corresponding to the symbol subject to subsampling, wherein the coding apparatus codes symbols while adaptively employing subsampling.