A fuel injection method for an internal combustion engine, an injection being implemented either in homogeneous normal operation or in inhomogeneous stratified operation. When used in conjunction with fixed-point arithmetic, this method increases the precision of the encoded and decoded results. When a number of image formation media on which images have been formed is smaller than a upper limit, the feeding mode is returned from the large spacing mode to the small spacing mode. At the same time, information about a computer bootstrap mode is stored in a recording device, the information representing a mode to start a conventional operating system or a mode to start a backuprecovery function.