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.
