3. The electronic filing system according to claim 1 , wherein the input document to be converted by the conversion unit is a structured document.
1. An electronic filing system for registering a document, comprising: at least one processor coupled via a bus to a memory, the processor being programmed to control one or more of: a style-sheet setting unit configured to set any one of a plurality of style sheet data to any one of a plurality of folders, wherein a portion of a document is emphasized by converting the document using the set style sheet data, the portion of the document to be emphasized being different depending on each style sheet data; an input unit configured to input a document to be registered into one of the plurality of folders, the one of the plurality of folders being specified by a user; a style-sheet acquisition unit configured to acquire the style sheet data set to the specified folder into which the document is input by the input unit; a conversion unit configured to convert the input document using the style sheet data acquired by the style-sheet acquisition unit to obtain the input document of which a portion corresponding to the acquired style sheet data has been emphasized; a reduced-image generation unit configured to generate a reduced image from the obtained document of which the portion corresponding to the acquired style sheet data has been emphasized, wherein the reduced image itself provides a preview of a portion of the document; and a registration unit configured to link the reduced image generated by the reduced-image generation unit to the input document being stored into the specified folder.