Image forming apparatus and image forming method for forming image on image forming medium

An image forming apparatus comprising:

• an image forming device discharging ink onto an image forming medium based on image data to form an image;
• a conveyance device having a conveyance path for conveying the image forming medium to the image forming device;
• a medium reading device acquiring, on the conveyance path, medium image data representing the image forming medium;
• and
• a control device including a processor and functioning as an abnormality detector and an abnormality related information output device as a result of executing a control program by the processor, wherein
• the abnormality detector uses the image data to generate contrast image region data for specifying an image formation target region that is a region targeted for image formation, uses the medium image data to generate contrast medium region data for specifying an image formation permitted region that is a region on the image forming medium where the image formation is enabled, and contrasts the contrast image region data and the contrast medium region data to detect, as an abnormal region, the image formation target region present outside of the image formation permitted region or a region corresponding to deficiency present within the image formation permitted region,
• the abnormality related information output device uses the medium image data to output abnormality related information that is information related to the abnormal region, and
• the image forming device is capable of limiting discharge of the ink onto the abnormal region.