1. A computer system for associating keywords with images included in a source, the source comprising one or more sections, the system comprising: an extraction component configured to extract text and related text metadata, and images and related image metadata, from the one or more sections of the source; a first data store configured to store at least the text and related text metadata extracted from the one or more sections of the source; a second data store configured to store at least the images and related image metadata extracted from the one or more sections of the source; and a relevance engine configured to: identify a type of the source; determine at least one keyword from the text and related text metadata stored in the first data store, wherein at least part of the related text metadata describes the text from which the at least one keyword is determined; select at least one relevance technique, out of a plurality of relevance techniques, based on the identified type of the source; and generate an association of the determined at least one keyword with at least one image and related image metadata stored in the second data store using the at least one relevance technique selected based on the identified type of the source, wherein each of the selected at least one relevance technique utilizes at least in part the related text metadata and the related image metadata to calculate a relevance score for determining whether to generate the association, and wherein the relevance score is weighted based at least in part on a suitability of the at least one relevance technique for the identified type of the source, wherein the generated association is recorded in a relevance index, and wherein the association is used to access the at least one image associated with the keyword in response to a search query including the keyword.