An image processing system comprises an image forming apparatus and a plurality of image processing servers. An image processing server transmits a test image to a plurality of image processing servers in charge of a former image processing operation, collects test results from all of them, and selects one of the image processing servers having returned the test results which are judged as being equal to or higher than a standard value, as the most preferred server, while an image forming apparatus transmits a test image to a plurality of image processing servers in charge of a final image processing operation, collects test results from all of them, and selects one of the image processing servers having returned the test results of the final image processing operation which are judged as being equal to or higher than a standard value, as the most preferred server.