An image data generation method and apparatus, an image distribution system and an image distribution device, the programs

And a distribution means for distributing the image dividing unit and the divided image data to divide the JPEG image stored as the image data storing means for storing image data of the JPEG format to the client, the image dividing means required for display on the client the tile area determining including an image area, from the image data stored in the image data storage means takes out the coefficient data corresponding to the tile region, among the coefficient data, the raw value for the AC component, the DC component is calculated as the coefficient data to deliver the result of adding the value of the DC component of the tile area before one adjacent to the client, the delivery means is delivered to the client the coefficient data calculated as image data.