Image quality stabilization processing

An image forming apparatus comprising:

• an image forming unit configured to conduct first image formation processing using a first single color material and second image formation processing using a second multicolor (Y,M,C,K) material;
• and
• a controller configured to perform image quality stabilizing processing for first image formation processing, wherein the image quality stabilizing processing operations performed by the controller further comprise:
• conducting a second image processing to print a test pattern using a black (K) color of the second multicolor material;
• detecting a position, a shape and a concentration of the test pattern;
• calculating a magnification deviation and inclination deviation of the test pattern from a predefined model;
• and
• correcting a write position of a drum associated with the imaging forming unit on which the first image formation processing is conducted based on the magnification deviation and the inclination deviation,
• wherein the controller receives a setting which indicates whether image quality stabilizing processing for first image formation processing is to be performed in either a first mode using the first color material or a second mode using the second multicolor material, wherein the first mode is an image quality priority mode, and the second mode is an economic efficiency priority mode.