Image transmission apparatus using information on rendered range

Abstract

An apparatus for transmitting image data through a network has an image rendering unit, an image processing device, a memory device, and an image transmitter. The image processing device is configured (a) to define a range surrounding an updated portion which has changed through displaying, of the displayed image sent from the image rendering unit, and to acquire position and range information of the defined range, (b) to compare the defined range with a range stored in the memory device, using the position and range information of the defined range and position and range information stored in the memory device, (c) to send the position and range information of the defined range to the memory device if there is no overlapping range between the compared ranges, and if there is an overlapping range between the compared ranges, to send position and range information of a new range surrounding the compared ranges to the memory device, and (d) when the image transmitter is ready for transmission through the network, to read image data of a latest image stored in the memory device, the image data corresponding to each item of the position and range information stored in the memory device at a time of transmission, to compress the image data in order to generate compressed image data, send the compressed image data to the memory device, and to initialize the position and range information stored in the memory device.