Image forming apparatus performing image density control based on developer amount

An image forming apparatus to which a process cartridge is attachable,

• wherein the process cartridge is configured to include:
• an image bearing member of which surface is exposed based on image data to form an electrostatic latent image on the surface;
• a developer bearing member which develops the electrostatic latent image by developer to form a developer image;
• an accommodating chamber which contains the developer;
• and a memory,
• wherein the image forming apparatus comprises:
• a detecting unit configured to emit light to a patch of the developer image, detect reflected light, and output information on the reflected light, and
• a control unit configured to perform image density control on the process cartridge, to control image density when forming the developer image, based on a value of the image data and information related to the reflected light,
• wherein the memory stores information corresponding to a developer amount contained in the accommodating chamber, and
• wherein the control unit controls to change a pattern of the patch to be used for the image density control, between a case where the information in the memory is first information corresponding to a case of the developer amount being a first amount, and a case where the information is second information corresponding to a case of the developer amount being a second amount, which is different from the first amount.