PURPOSE: To dissolve the unevenness of a density by setting a reference image information range based on a characteristic value of a cumulative histogram of pre-read information, and executing a regular read in accordance with a read condition which has been set so that the reference image information range corresponds to a prescribed electric image signal range.
CONSTITUTION: A cumulative histogram is generated extending over the whole range of pre-read image information. Subsequently, a characteristic value Sc of the cumulative histogram of the pre-read image information is derived, and based on said value, a reference image information range is set. A reference image information range A is set, and a read condition is set so that said range A corresponds to a prescribed electric image signal range, that is to say, an accelerated luminous light quantity Sc-a2 and Sc+a1 are outputted from a photoelectric read means as an electric image signal Qmin, and Qmax, respectively. In accordance with this read condition, a regular read is executed, and an electric image signal for outputting a visible image is obtained.
ISHIDA MASAMITSU
ADACHI YUUMA
NAKAJIMA NOBUYOSHI
