An imaging apparatus, comprising: an image pickup unit picking up a subject image and generating image data; characterised by an operating unit accepting, from a user, an operation of selecting, before said image pickup unit picks up the subject image, any one of a first photographic mode that does not perform a gradation compression processing of improving lightness of a dark area gradation of said image data and a second photographic mode that performs the gradation compression processing of improving lightness of the dark area gradation of said image data; a gradation conversion processing unit performing a gradation conversion processing according to a first input-output characteristic on the image data generated by said image pickup unit in said first photographic mode when said first photographic mode is selected, and performing a gradation conversion processing according to a second input-output characteristic different from said first input-output characteristic on the image data generated by said image pickup unit in said second photographic mode when said second photographic mode is selected; a low-pass processing unit generating a low-pass image by applying a low-pass filter on image data being gradation converted by said gradation conversion processing unit; and a gradation compression processing unit performing the gradation compression processing of improving lightness of the dark area gradation on image data subjected to the gradation conversion processing according to said second input-output characteristic by said gradation conversion processing unit using said low-pass image generated by said low-pass processing unit when said second photographic mode is selected. an image pickup unit picking up a subject image and generating image data; characterised by an operating unit accepting, from a user, an operation of selecting, before said image pickup unit picks up the subject image, any one of a first photographic mode that does not perform a gradation compression processing of improving lightness of a dark area gradation of said image data and a second photographic mode that performs the gradation compression processing of improving lightness of the dark area gradation of said image data; a gradation conversion processing unit performing a gradation conversion processing according to a first input-output characteristic on the image data generated by said image pickup unit in said first photographic mode when said first photographic mode is selected, and performing a gradation conversion processing according to a second input-output characteristic different from said first input-output characteristic on the image data generated by said image pickup unit in said second photographic mode when said second photographic mode is selected; a low-pass processing unit generating a low-pass image by applying a low-pass filter on image data being gradation converted by said gradation conversion processing unit; and a gradation compression processing unit performing the gradation compression processing of improving lightness of the dark area gradation on image data subjected to the gradation conversion processing according to said second input-output characteristic by said gradation conversion processing unit using said low-pass image generated by said low-pass processing unit when said second photographic mode is selected.