A clock signal is frequency-modulated and an image processing operation is executed
synchronously with the frequency-modulated clock signal to generate image data
which is stored in a memory. Image data written in the memory is read synchronously
with a clock signal having a fixed frequency. The image data written in the memory
synchronously with the frequency-modulated clock signal is therefore converted
into the image data synchronizing with the clock signal having a fixed frequency.
Data subjected to image processing synchronously with the frequency-modulated clock
signal can be output on the recording apparatus side without any practical problem.
