Defective recording element detecting apparatus and method, and image forming apparatus and method

A defective recording element detecting apparatus, comprising:

• a read image data acquiring device which acquires read image data of a test pattern recorded on a recording medium by a recording head having a plurality of recording elements;
• a reference area setting device which sets a reference area including a part of the test pattern on a read image representing image contents of the read image data;
• a comparison area setting device which sets a comparison area to be compared with the reference area on the read image;
• a correlation operation device which performs a correlation operation between the comparison area and the reference area while relatively shifting the comparison area with respect to the reference area;
• a distortion correction value determining device which determines a distortion correction value for correcting an amount of deviation of an image in the comparison area with respect to an image in the reference area, from a result of the correlation operation;
• an image distortion correcting device which corrects image distortion of the read image using the distortion correction value;
• and
• a defective recording element determining device which identifies a defective recording element among the plurality of recording elements of the recording head in accordance with the read image having been corrected by the image distortion correcting device.