Image forming apparatus and image forming method

An image forming apparatus comprising:

• a latent image bearer;
• an electrostatic latent image forming device to form an electrostatic latent image on the latent image bearer;
• a potential sensor to detect an electric potential on the latent image bearer;
• a toner image forming device to form a toner image based on the electrostatic latent image;
• a toner adhesion amount detector to detect a toner adhesion amount of the toner image;
• and
• circuitry to:
• control the electrostatic latent image forming device to create an adjustment pattern on the latent image bearer during a non-printing period in which the image forming apparatus is not printing,
• control the potential sensor to detect an electric potential of the adjustment pattern,
• control the electrostatic latent image forming device and the toner image forming device to create a test toner image during a printing period,
• control the toner adhesion amount detector to detect a toner adhesion amount of the test toner image, and
• adjust at least one image forming condition of the electrostatic latent image forming device and the toner image forming device based on the electric potential of the adjustment pattern and the toner adhesion amount of the test toner image.