An image processing apparatus for capturing an image of an object and thereby performing an optical area division of a surface of the object, comprising: an illumination unit including an illumination section and being capable of changing at least one of a polarization state of light emitted from the illumination section and a position of the illumination section; an illumination control section for changing the polarization state of light emitted from the illumination section; a polarization image capturing section for obtaining a polarization image of the object by receiving light having passed through a polarizer having at least three different polarization main axis angles; a control section for synchronizing the changing by the illumination unit of at least one of the polarization state of light emitted from the illumination section and the position of the illumination section with the image-capturing by the polarization image capturing section; a polarization information obtaining section for generating, from the obtained polarization image, polarization information for received polarized light by using a correspondence with a brightness of the light having passed through the polarizer, for each of unit pixels of the polarization image; a light source dependency estimation section for estimating light source dependency information which represents a degree of change in the polarization state of the light received from the surface of the object occurring when the at least one of the polarization state and the position of the illumination section is changed, said light source dependency information being estimated by making a comparison between the polarization information generated by the polarization information obtaining section when the at least one of the polarization state and the position of the illumination section is changed by the illumination control section; an area dividing section for performing the area division based on the polarization information and the light source dependency information. an illumination unit including an illumination section and being capable of changing at least one of a polarization state of light emitted from the illumination section and a position of the illumination section; an illumination control section for changing the polarization state of light emitted from the illumination section; a polarization image capturing section for obtaining a polarization image of the object by receiving light having passed through a polarizer having at least three different polarization main axis angles; a control section for synchronizing the changing by the illumination unit of at least one of the polarization state of light emitted from the illumination section and the position of the illumination section with the image-capturing by the polarization image capturing section; a polarization information obtaining section for generating, from the obtained polarization image, polarization information for received polarized light by using a correspondence with a brightness of the light having passed through the polarizer, for each of unit pixels of the polarization image; a light source dependency estimation section for estimating light source dependency information which represents a degree of change in the polarization state of the light received from the surface of the object occurring when the at least one of the polarization state and the position of the illumination section is changed, said light source dependency information being estimated by making a comparison between the polarization information generated by the polarization information obtaining section when the at least one of the polarization state and the position of the illumination section is changed by the illumination control section; an area dividing section for performing the area division based on the polarization information and the light source dependency information.