1. A method of processing data associated with a document requested by a client device from a server, the document being represented by image data, the image data having one or more data values and color levels, the method comprising: predefining a set of relationships between zoom levels and tonal reproduction curves in one or more client dependent image processing tables; automatically determining one or more parameters associated with at least one of a client device display and a data network for transmitting the image data from the server to the client device, based on a type and/or content of the document requested, the one or more parameters comprising an image data display zoom level requested by the client device; and processing image data by enhancing a contrast of the data values using a tonal reproduction curve based on the one or more parameters determined, the tonal reproduction curve being selected, based on the requested zoom level, from the predefined set of relationships stored in the one or more client dependent image processing tables, said processing being performed by the server prior to transmitting the image data to the client device.