To transfer an image data by a format without the loss time such as seek time so as to be fit for an output device in a short time in the case the image is recorded by a plurality of light beams per one main scanning operation of the output device.

In the case of recording simultaneously three lines of image data of raster image data type, the data order is converted at the time of storage into line buffers or at the time of reading out of the line buffers so that a first image data of the three lines appears first to eliminate the reduction of speed generated by the seek time (mechanical operation time) required for taking out the required data at the time of reading the image data out of a hard disk 112. Also DRAM 200A, 200B and 200C, the number of which corresponds to the number of simultaneous record scanning lines, are provided to carry out the burst transfer.