1. A computing device for determining relevance of a document to a text string, the document containing text and images, the text and the text string having terms, comprising: a memory storing computer-executable instructions implementing a component that, for each of a plurality of images contained in the document, identifies text associated with the image by extracting text from the document that is determined to be adjacent to the image, the extracted text being the identified text that is associated with the image; a component that, for each of the plurality of images, determines relevance of the identified text associated with the image to the text string based on comparison of terms of the identified text to terms of the text string; and a component that determines relevance of the document to the text string based on the determined relevance of the identified text associated with each of the plurality of the images to the text string; and a processor for executing the instructions stored in the memory.