1. An image processing method for extracting a region having a specific feature, the image processing method comprising: extracting pixels representing an object, to which the pixel having the specific feature belongs, from a given input image based on an image feature other than color; extracting principal colors from the pixels; selecting, from a plurality of pre-trained color distribution models deposited in a repository, a color distribution model closest in a distance metric to the extracted principal colors by performing a search through the repository using the extracted principal colors, the distance metric indicating distance relative to the extracted principal colors; segmenting the input image by categorizing pixels in the input image using the selected color distribution model; and modifying a Gaussian mixture model (hereinafter, “GMM”) obtained from the input image based on score values of components of the GMM obtained from the input image, wherein in the step of modifying: a score value is an output obtained by inputting a mean of the components of the GMM of the input image to the GMM deposited in the repository, the score value of each of the components of the GMM of the input image is compared with a predetermined threshold value, any component of which score value is equal to or lower than the threshold value of the components is deleted from the GMM of the input image, and weights of remaining components, the remaining components being the components of the GMM of the input image exclusive of the deleted component, are re-defined so that a sum of the weights of the remaining components is one.