Patent ID: 7999863

Claim:
An image correction apparatus comprising: a brightness correcting device for correcting subject image data, which represents the image of a subject, in such a manner that the brightness of a target image, which is one portion within the image of the subject, will take on a prescribed target value; a noise reduction parameter deciding device for deciding a noise reduction parameter based upon an amount of correction applied in said brightness correcting device; a noise reducing device for applying noise reduction processing to the subject image data, which has been corrected by said brightness correcting device, based upon the noise reduction parameter decided by said noise reduction parameter deciding device; wherein said brightness correcting device is a gamma correction circuit for applying a gamma correction to the subject image data based upon a revised gamma correction curve according to which the brightness of the target image takes on the prescribed target value; a first histogram calculating device for calculating a histogram of image data obtained in a case where the target image data has been subjected to gamma correction using a basic gamma correction curve; a threshold value deciding device for deciding a threshold value based upon the histogram calculated by said first histogram calculating device: a revised gamma correction curve calculating device for calculating a revised gamma correction curve based upon an ideal value of brightness of the target image: a second histogram calculating device for calculating a histogram of image data obtained in a case where the target image data has been subjected to gamma correction using the revised gamma correction curve calculated by said revised gamma correction curve calculating device; and a loop control device for executing processing that lowers the level of the ideal value until a peak value of the histogram that is calculated by said second histogram calculating device falls below the threshold value decided by said threshold value deciding device, and controlling said revised gamma correction curve calculating device and said second histogram calculating device so as to repeat revised correction curve calculation processing that is based upon the ideal value whose level has been lowered and gamma correction processing that uses the revised correction curve; wherein the ideal value at which the peak value of the histogram falls below the threshold value calculated by said second histogram calculating device is adopted as the prescribed target value of brightness of the target image, and the subject image data is subjected to the gamma correction based upon the revised correction curve according to which the brightness of the target image takes on the prescribed target value.