To suppress the deterioration of image quality by eliminating the intermittent operation of read in an image reader, and to measure the transfer speed of image data from the image reader to a host computer in a short time, without having to depend on the capacity of a buffer memory inside the image reader.

This image read method is provided with a dummy data request step for requesting dummy data for measuring an image transfer speed from the host computer 2 to a scanner 1, which is the image reader, a dummy data transfer step for transferring the dummy data from the scanner to the host computer according to the request, an image transfer speed calculation step for calculating the image transfer speed in the host computer from the transferred dummy data, an image transfer speed report step for reporting calculated image transfer speed information to the scanner, and a read speed setting step for setting the read speed of images in the scanner, based on the reported image transfer speed information.