CHAPTER 3 IMAGE READING/PROCESSING SYSTEMCOPYRIGHT © 2002 CANON INC. 2000 CANON iR1600/iR2000 REV.1 JAN. 20023-184.12 Binary ProcessingThe machine uses an error diffusion method to covert 8-bit (256-gradation) image datainto 1-bit (binary) image data.4.12.1 Error DiffusionTo convert 8-bit (256-gradation) image data into 1-bit (2-gradation) image data, the ma-chine tries to find out whether the level of a specific image signal is higher or lower than athreshold level: 8-bit image data (0 through 255) into 2-bit image data (0, 1). At this time,the difference of the signal from the threshold level is “diffused” to its adjacent signals (pix-els) to express the gradation (dark, light) of the original image.4.13 Image Memory ControlThe image memory is used as follows:4.13.1 Compression/Expansion, Rotation, and Enlargement/ReductionThe machine uses image memory to subject binary image signals to compression/expan-sion, rotation, and the like.4.13.2 SDRAMThe machine uses image memory to store image data for image memory functions.REF.The machine is designed for memory copying only (no direct copying). Themachine stores the image data once in its memory before generating output,at times resulting in inadequate available space when continuous copying isunder way with the ADF in use. In such an event, the machine will stopreading the original, generate copy output, and resume reading when ad-equate space has been created.
