1. An image processing apparatus comprising: a scanner for obtaining document images by reading out documents, respectively, a first extraction unit for extracting text contained in the document images, a second extraction unit for extracting at least one Web address from the text, a fetch unit for obtaining at least one Web page corresponding to the Web address through a network by using a Web browser, a first generation unit for generating a concatenated image by concatenating the document images with the Web page, and a second generation unit for generating an index indicating a corresponding relationship between the document images and the Web page in the concatenated image.