1. An image processing method utilizing a computer to perform the steps of: a detection step comprising: detecting a correspondence between one color of a first plurality of colors in a first image and one color of a second plurality of colors in a second image, detecting a plurality of correspondences between a first plurality of feature colors and a second plurality of feature colors by extracting said first plurality of feature colors featuring said first image from said first image and extracting said second plurality of feature colors featuring said second image from said second image, making a first decision of deciding said first plurality of feature colors in accordance with an extent of appearance of said first plurality of colors, and making a second decision of deciding said second plurality of feature colors in accordance with an extent of appearance of said second plurality of colors; and a correction step of correcting said first plurality of colors or said second plurality of colors in accordance with said correspondence.