1. An image processing apparatus adapted to execute image processing which converts a raw image into vector data, the image processing apparatus comprising: a segmentation unit adapted to segment the raw image into region images for each attribute; a cutout unit adapted to cut out region images segmented by the segmentation unit according to attribute from the raw image; a determination unit adapted to determine at least one representative color configuring the region image cut out by the cutout unit, based on an appearance color of the region image; an image extraction unit adapted to extract a color image having the representative color determined by the determination unit from the region image; a contour line extraction unit adapted to extract a contour line of a color image extracted by the image extraction unit; an edge image extraction unit adapted to extract an edge image within the region image; a correction unit adapted to correct a contour line extracted by the contour line extraction unit based on an edge image extracted by the edge image extraction unit; and a generation unit adapted to generate vector data of the region image using contour lines corrected by the correction unit.