Image forming apparatus and image forming method

An image forming apparatus comprising:

• an image forming device configured to form an image on a recording medium;
• a fixing body configured to fix the image formed on the recording medium to the recording medium;
• a branching portion configured to change a direction of the recording medium on which the image is formed, between a direction toward an outside of the image forming apparatus and a direction to a passage conveying the recording medium in a different direction from the direction toward the outside of the image forming apparatus;
• a reading device configured to scan the recording medium having a position detection mark on the recording medium as the image and generate a scanned image,
• the reading device being disposed between the fixing body and the branching portion in a sheet conveying direction of the recording medium;
• and
• circuitry configured to calculate a correction value to adjust a position of the image to be formed on the recording medium, based on the scanned image.

An image forming method comprising:

• forming an image on a recording medium;
• scanning a first face of the recording medium having a position detection mark on the recording medium;
• generating a first scanned image from the first face of the recording medium;
• and
• calculating a correction value to adjust a position of an image to be formed on a second face of the recording medium based on the first scanned image generated from the first face of the recording medium, within a period from when the first scanned image is generated from the first face of the recording medium to when the image starts to be formed on the second face of the recording medium.