1. A method of seeking one or more representative images in an image set including plural images stored in an electronic image database accessible by computer hardware, the method comprising: a text feature extracting step of extracting, by a processor of the computer hardware, one or more text features of each of the plural images in the image set based on original data of the corresponding images and/or annotation information input by a user, the text feature extracting step including: (1) a text keyword database creating step of creating a text keyword database of the image set based on the original data of all the images in the image set and/or the annotation information input by the user, (2) a text feature space creating step of creating a text feature space by selecting one or more text keywords from the text keyword database of the image set, the dimension of the text feature space being equal to the number of the selected text keywords, the text feature space creating step including: (i) an appearance frequency calculating step of calculating an appearance frequency of each of the text keywords appearing in the text keyword database of the image set, and (ii) a text keyword selecting step of selecting one or more of the text keywords whose appearance frequencies are in a predetermined range so as to create the text feature space, and (3) a text feature forming step of forming the text features of each of the plural images by using the text feature space based on the original data of all the images in the image set and/or the annotation information input by the user; a diversity data obtaining step of obtaining diversity data of the image set based on the text features of each of the plural images in the image set, wherein, the diversity data is used to express discrepancies between contents of any two images in the image set; a representative score calculating step of calculating a representative score of each of the plural images based on the diversity data of the image set, wherein, the representative score is used to express a representativeness of a content of each of the plural images with regard to contents of all the images in the image set; a sorting step of sorting the representative scores of each of the plural images; and a representative image selecting step of selecting, based on the sorting, one or more of the images in the image set based on the representative score of each of the plural images in the image set, wherein, the one or more images represent the contents of all the images in the image set, and serve as the one or more representative images.