PURPOSE: To prevent the deterioration in the color reproducibility by revising configuration of learning data based on the degree of achievement of learning for each preset conduction in the case of implementing the learning by the back propagation method.

CONSTITUTION: A printer control signal generated by a learning system 20 is given to a recording system 40 to output a color hard copy and its output is read photoelectrically by a color separation system 30. Then the learning system 20 uses a printer control signal given to the recording system 40 as a teacher signal, uses a color separation signal outputted from the color separation system 30 as an input signal and uses the input signal and the teacher signal as learning data so as to apply learning by the back propagation method and the configuration of the learning data is revised based on the degree of achievement of learning for each preset condition during the continuity of learning. Thus, an error as the entire learning data is reduced and the deterioration in the reproducibility around a specific color is improved.