PURPOSE: To attain multi-value processing in response to the desire of the operator by providing a multi-value processing control section employing an n→m processing means designated by the input so as to apply m-value processing to an n-value data.

CONSTITUTION: The device is provided with plural different n→m processing means applying m-value processing (n<m) to an n-value picture data, an input section selecting the n→m processing means and a multi-value processing control section applying m-value processing to an n-value data through the use of the n→m processing means designated by the input from the input section. Then the n→m processing means designated by the operator among the plural n→m processing means is used for the multi-value processing. Thus, the multi-value processing in which the preference of the operator has the highest priority is attained.