1. A method comprising the steps of: providing a processor with a first set of digital information comprising a first structured representation of a document, the first structured representation being a resolution-independent representation, a plurality of image collections being obtainable from the first structured representation, each such obtainable image collection comprising at least one image, each image in each such collection being an image of at least a portion of the document, each image in each such collection having a characteristic resolution; with a processor, generating a first bitmap representation of the document with the first structured representation, the first bitmap representation comprising an image collection including at least one image, each image in the image collection comprised by the first bitmap representation being an image of at least a page of the document; each image in the first bitmap representation having a first characteristic resolution; with a processor, producing from the first bitmap representation a second set of digital information comprising a second structured representation of the document, the second structured representation being a lossless representation of a low-resolution image collection, the second structured representation including a plurality of low-resolution tokens and a plurality of positions, the second set of digital information being produced by extracting the plurality of low-resolution tokens from the first bitmap representation, each low-resolution token comprising a set of pixel data representing a subimage of the low-resolution image collection, and determining from the first bitmap representation the plurality of positions of the second structured representation, each position of the second structured representation being a position of a low-resolution subimage in the low-resolution image collection, each low-resolution subimage being one of the subimages from one of the plurality of low-resolution tokens, at least one low-resolution subimage having a plurality of pixels and occurring at more than one position in the image collection; with a processor, generating a second bitmap representation of the document with the first structured representation, the second bitmap representation comprising an image collection including at least one image, each image in the image collection comprised by the second bitmap representation being an image of at least a page of the document; each image in the second bitmap representation having a second characteristic resolution; the second characteristic resolution being greater than the first characteristic resolution; with a processor, producing from the second bitmap representation a third set of digital information comprising a third structured representation of the document, the third structured representation being a lossless representation of a high-resolution image collection, the third structured representation including a plurality of high-resolution tokens and a plurality of positions, the third set of digital information being produced by extracting the plurality of high-resolution tokens from the second bitmap representation, each high-resolution token comprising a set of pixel data representing a subimage of the high-resolution image collection, and determining from the second bitmap representation the plurality of positions of the third structured representation, each position of the third structured representation being a position of a high-resolution subimage in the high-resolution image collection, each high-resolution subimage being one of the subimages from one of the plurality of high-resolution tokens, at least one high-resolution subimage having a plurality of pixels and occurring at more than one position in the image collection; and making the second and third sets of digital information thus produced available for further use.