Image processing method, apparatus and controller

An image forming unit comprising a central processing unit executing a method comprising the steps of:

• performing bi-directional communication with a controller;
• receiving image data from the controller to form a color image by using the bi-directional communication;
• transmitting a status of the image forming unit to the controller by using bi-directional communication;
• receiving from the controller a command, which indicates execution of a calibration of a condition of color processing, by using the bi-directional communication;
• controlling formation and measurement of a patch by the image forming unit in accordance with the received command;
• and
• transmitting patch data obtained in said controlling step to the controller by using the bi-directional communication,
• wherein the controller calculates controller color-correction data based on the patch data and performs color correction using the controller color-correction data so as to generate color image data to be outputted to the image forming unit.

A controlling method of a controller comprising the steps of:

• performing bi-directional communication with the image forming unit;
• receiving a status of the image forming unit from the image forming unit by using the bi-directional communication;
• deciding timing for a calibrating condition of color processing based on the received status;
• transmitting to the image forming unit a command, which indicates execution of calibration of the condition of color processing, by using the bi-directional communication;
• receiving from the image forming unit patch data, which is obtained by measuring a patch formed by the image forming unit, by using the bi-directional communication;
• calculating controller color-correction data based on the received patch data;
• and
• performing color correction using the controller color-correction data so as to generate color image data to be outputted to the image forming unit,
• wherein the image forming unit has a central processing unit which controls the formation and measurement of the patch in accordance with the command received in said transmitting step.