Image forming apparatus and image forming method

An image forming apparatus comprising:

• an exposure device including a plurality of lighting elements aligned in a main scanning direction,
• the exposure device being configured to drive the plurality of lighting elements to form a first test image;
• a reader configured to read the first test image;
• and
• circuitry configured to:
• divide the first test image into a plurality of first sub-areas in the main scanning direction to acquire density data of the plurality of first sub-areas;
• and
• calculate first correction data based on density data of each of the plurality of first sub-areas and average density data of the plurality of first sub-areas, to correct a light amount of the plurality of lighting elements based on the first correction data calculated, the first correction data being density correction data for each of the plurality of first sub-areas,
• the exposure device being configured to form a second test image with the light amount of the plurality of lighting elements corrected,
• the reader being configured to read the second test image,
• the circuitry being configured to:
• divide the second test image into a plurality of second sub-areas in the main scanning direction to acquire density data of the plurality of second sub-areas, the plurality of second sub-areas having a different location from a location of the plurality of first sub-areas in the main scanning direction;
• and
• calculate second correction data based on density data of a second sub-area adjacent to each of the plurality of second sub-areas, to further correct the light amount of the plurality of lighting elements based on the second correction data calculated, the second correction data being density correction data for each of the plurality of second sub-areas.