Patent ID: 8918450

Claim:
An image transfer system, comprising a server apparatus, which causes drawing data created at the server apparatus to be transmitted to a client apparatus and displayed on a display screen of the client apparatus, the server apparatus comprising: a drawing data storage unit which stores preceding drawing data on a preceding screen transferred to the client apparatus and present drawing data on a created present screen; an area dividing unit which divides drawing data into a plurality of drawing areas; a specific data converting unit which compares the present drawing data with the preceding drawing data for each of the drawing areas, and converts pixels of drawing data of a portion having no change into specific data in each of the plurality of drawing areas in the present drawing data, wherein the specific data comprises data that identifies the converted pixels as being associated with no change with reference to the preceding drawing data; a specific drawing area detecting unit which detects a specific drawing area having both the specific data converted by the specific data converting unit and the drawing data of a portion which has a change in the present drawing data from the preceding drawing data; a compressing unit which compresses drawing data corresponding to the specific drawing area; and a transmission control unit which transmits, to the client apparatus, the compressed drawing data; wherein the specific data requires no rewriting when the client apparatus displays the compressed drawing data.