| 摘要 |
Positions in a main scanning direction of points of exposure are determined by emission of light from two light-emitting points of each exposure device near predetermined endmost light-emitting points. A first exposure device of which a distance between the two light-emitting points is greatest is identified based on the determined positions of the points of exposure. A subset of usable light-emitting points of a second exposure device other than the first exposure device, located in positions corresponding to a range of exposure which coincides in a width direction with a range of exposure defined by the two light-emitting points of the first exposure device, is specified The number n of pairs of adjacent usable light-emitting points of the second exposure device each associated with one pixel is obtained by subtracting the number of usable light-emitting points of the first exposure device from that of the second exposure device. |
