A CPU 231 calculates modified brightness correction amount tCurve_Y with consideration of exposure correction amount (or exposure value) EV if photography information PI (or Exif IFD) is included in image data GF. Specifically, the modified brightness correction amount tCurve_Y is calculated by dividing original brightness correction amount tCurve_Yorg by 2|EV|. Therefore, it decreases in geometrical progression as the exposure correction amount increases. The CPU 231 applies the obtained modified brightness correction amount tCurve_Y to a tone curve to adjust image quality including brightness. More specifically, it uses the modified brightness correction amount tCurve_Y to modify the characteristics of the tone curve, and then uses the modified tone curve to adjust the image quality of the image data.