1. An apparatus, comprising a processor, in which luminance values of an input image are converted for output, comprising: a first extracting unit configured to extract first image information from a first region including a target pixel; a first calculating unit configured to calculate a first conversion characteristic from the first image information; a second extracting unit configured to extract second image information from a second region including the first region; a second calculating unit configured to calculate a second conversion characteristic from the second image information; a weighted coefficient calculating unit configured to calculate a weighted coefficient based on position information of the target pixel; a frame characteristic calculation unit configured to calculate a value so that the value is kept close to a constant proportion to conversion characteristics of a preceding single frame, the value being a difference value between the second conversion characteristic of the preceding single frame and the second conversion characteristic of a current frame; and a third calculating unit configured to calculate a third conversion characteristic for converting a luminance value of the target pixel, using the first conversion characteristic, the second conversion characteristic, and the weighted coefficient, wherein the luminance value of the target pixel is converted and outputted based on the third conversion characteristic.