An object of the invention is to process image data the quality by simply uploading the image data prepared by the user himself himself to a server of a provider without using a particular hardware equipped with an image quality correction function, without the need of purchasing and using a software for correcting the image quality, and without caring about anything. In a system including personal computers 2a, 2b, 2c, - - - of the clients and a server 1 of a provider, when image data are uploaded to the server 1 of the provider from the personal computers 2a, 2b, 2c, - - - of the clients, the quality image of the image data is corrected by the server 1.