1. An image processing method in an image processing apparatus for inputting a color document image including a clipart image having an area of gradation, and converting the clipart image into vector data, comprising: a selecting step of selecting the clipart image from the input color document image; an extracting step of extracting outline information of the clipart image; a separating step of separating the color document image into an achromatic color area and a chromatic color area; a dividing of region step of respectively dividing the achromatic color area and the chromatic color area into a plurality of regions; an integrating of region step of integrating regions which meet a set condition of the plurality of regions of each of the achromatic color area and the chromatic color area divided in the dividing of region step; and a converting step of converting the clipart image into vector data using region groups integrated in the integrating of region step and the outline information.