An image processing apparatus for processing a radiation image obtained from a radiation detector capable of releasing or accumulating electric charges for each row, comprising: a target value setting unit configured to set a target value of each pixel on a correction target row in the radiation image based on pixel values on a row adjacent to the correction target row； a pixel selection unit configured to select an effective pixel on the correction target row based on a pixel value and the target value of each pixel on the correction target row； and a correction unit configured to derive a correction coefficient using a pixel value and the target value of the effective pixel and correct the correction target row based on the correction coefficient.
