The presence or absence of outside light is individually decided with respect to each of the time of executing AFE adjusted value acquiring processing, the time of executing LED adjusted value acquiring processing and the time of executing black correction data acquiring processing. In the case of deciding that the outside light is present, a parameter in the case of deciding that the outside light is present is modified to a predetermined value or a reacquired value. As a result of this, even when an incident state of outside light changes at the time of acquiring each of the parameters, it can properly be switched whether or not their parameters are replaced with the predetermined value or the reacquired value.