The image forming apparatus and an image forming method

Discloses an image forming apparatus and an image forming method. In a conveying direction of the test card on which the image was measured. When the measurement image passes through the color sensor, they undergo pre-scan. Determining the cumulative time according to the color sensor for each measurement prescan image. Sequentially conveyed in a direction of a test card, and then change the conveying direction. In this manner, after the color sensor prescan images for all measurements, again conveyed toward the color sensor test card. When the test card again passes through the color sensor, the measurement image in the main scanning performed.