In a television set, image quality is adjusted in accordance with parameters calculated on the basis of adjustment values used in the past, depending on a feature of an image and an environmental status. A weight calculator determines a weight depending on the manner in which a user performs a volume control operation. A cumulative weight memory outputs a cumulative weight corresponding to the feature value. Output volume values used in past are stored in a volume value generator. The volume value generator calculates output volume values corresponding to a feature value on the basis of parameters indicating final adjustment values, the feature value, the weight, and the cumulative weight. The calculated volume values are stored in the volume value generator. Under the control of a system controller, the volume values stored in the volume value generator are output to a coefficient generator.