Patent ID: 7965967

Claim:
An image-forming device comprising: a pattern data generating unit configured to generate pattern data indicative of a pattern of a plurality of marks including a plurality of first marks each having a first color and a plurality of second marks each having a second color, such that: the plurality of first marks being located such that a sum of vector distances from each of the first marks to a first reference position in a predetermined direction defines a first value, the plurality of second marks being located such that a sum of vector distances from each of the second marks to the first reference position in the predetermined direction defines a second value, and the first value is equal to the second value; an image-forming unit configured to form color images on an object based on the pattern data; a detecting unit configured to detect actual positions of the plurality of first marks formed on the object and to detect actual positions of the plurality of second marks formed on the object; a calculating unit configured to calculate: a sum of the vector distances from the actual positions of the first marks to the reference position, a sum of the vector distances from the actual positions of the second marks to the reference position, and an offset between the sum of the vector distances of the actual positions of the first marks and the sum of vector distances of the actual positions of the second marks; and a controlling unit configured to control the image-forming unit to calibrate the locations of the second marks as output from the pattern data generating unit based on the offset.