An image processing apparatus, comprising: an input section (13, 20) adapted to acquire image data and information about subject luminance at a time of photographing said image data; an adjusting section adapted to determine a brightness enhancement amount for dark area gradation correction of said image data by a calculation which depends on said subject luminance (S5, S6); and a correcting section adapted to correct said dark area gradation of said image data according to said brightness enhancement amount determined by said adjusting section (S8, S9); characterised in that a smoothing process is performed on the image data to obtain a smoothing image (YL(x,y)); and in that said adjusting section is adapted to divide an image of said image data into a plurality of subregions, to allocate divided photometric data for each subregion, and determines a brightness enhancement amount (G(i)) for each of said subregions by performing weighting according to said subject luminance and location in the image, wherein weighting by location in the image is greater for subregions located at the center of the image than for subregions located at the fringe of the image, and to execute one of: an averaging process, a weighted averaging process, a maximal value calculating process, and a mode value and intermediate value calculating process of said brightness enhancement amount (G(i)) for each of said subregions, to determine one representative value of brightness enhancement amount (Mg) per image; and in that said correction section is adapted to correct said dark area gradation of said image data according to a gain map (GM(x,y)) obtained by multiplying each of a plurality of values of a function of pixel values of said smoothing image with said representative value (Mg) of brightness enhancement amount. an input section (13, 20) adapted to acquire image data and information about subject luminance at a time of photographing said image data; an adjusting section adapted to determine a brightness enhancement amount for dark area gradation correction of said image data by a calculation which depends on said subject luminance (S5, S6); and a correcting section adapted to correct said dark area gradation of said image data according to said brightness enhancement amount determined by said adjusting section (S8, S9); characterised in that a smoothing process is performed on the image data to obtain a smoothing image (YL(x,y)); and in that said adjusting section is adapted to divide an image of said image data into a plurality of subregions, to allocate divided photometric data for each subregion, and determines a brightness enhancement amount (G(i)) for each of said subregions by performing weighting according to said subject luminance and location in the image, wherein weighting by location in the image is greater for subregions located at the center of the image than for subregions located at the fringe of the image, and to execute one of: an averaging process, a weighted averaging process, a maximal value calculating process, and a mode value and intermediate value calculating process of said brightness enhancement amount (G(i)) for each of said subregions, to determine one representative value of brightness enhancement amount (Mg) per image; and in that said correction section is adapted to correct said dark area gradation of said image data according to a gain map (GM(x,y)) obtained by multiplying each of a plurality of values of a function of pixel values of said smoothing image with said representative value (Mg) of brightness enhancement amount.