In a contrast correcting apparatus 1 which divides an image into unit
regions and carries out a contrast correction for each of unit regions, a
gray level histogram calculation section 201 generates gray level
histograms of the image, and a scene judgment section 202 makes a
judgment on the state of the image. When the result of the judgment shows
that the image is in a state such as overexposure, underexposure, low
contrast or high contrast, a region size determining section 204 sets a
greater size as the size of the unit regions. Based upon the size of the
unit regions thus determined and the amount of contrast correction
determined by the contrast correction amount determining section 203,
gray level transformation curves are formed for the respective unit
regions, and by using these, the contrast corrections are carried out on
the respective unit regions. With this method, it is possible to properly
reduce the occurrence of unevenness in gray levels in an image that tends
to arise in the case when the size of the unit regions is small although
the amount of contrast correction (the amount of emphasis) is great.