Patent ID: 7874634

Claim:
An image forming apparatus which forms a halftone image on a print medium using multipass processing of reciprocally scanning a single area on the print medium by a printhead a plurality of number of times, forming dots on the print medium in one of reciprocal scan operations, and moving the printhead to a home position in the other reciprocal scan operation, the apparatus comprising: generator configured to generate print data of each print-scan operation; printing unit configured to print the halftone image on the print medium on the basis of the print data generated by the generator; and detector, in at least one print-scan operation out of a plurality of print-scan operations, configured to detect a state of printing on the print medium by the printing unit in up to a print-scan operation immediately preceding a print-scan operation of interest, wherein the generator corrects the print data in synchronism with printing by the printing unit on the basis of the printing state detected by the detector.