Distance measuring device, image forming apparatus, and distance measuring method

A device, comprising:

• an imaging unit, including an image sensor, configured to capture an image of a test pattern including at least a pair of first markers and a second marker that is formed under a condition different from a condition applied to the pair of the first markers;
• and
• processing circuitry configured to
• detect a position of each of the first markers and the second marker in the captured image;
• calculate a ratio of (1) a first captured distance between the pair of the first markers in the captured image, which is determined from the detected positions, and (2) a first actual distance between the pair of the first markers,
• calculate a second actual distance between one of the first markers and the second marker by multiplying a second captured distance between the one of the first markers and the second marker in the captured image, which is determined from the detected positions, by the calculated ratio, and
• calculate an amount of a positional deviation based on the calculated second actual distance, adjust, based on the positional deviation amount, a parameter related to an image forming position, and send the adjusted parameter to a controller of an image forming apparatus to control an image formation process.