| 摘要 |
PROBLEM TO BE SOLVED: To reduce computational complexity for detection as compared with the prior arts without reducing detection precision in positional deviation of an image. SOLUTION: An image forming apparatus forms a plurality of detection images each having a size determined with respect to a (y) direction at intervals (d) each determined with respect to the direction while using single toner. The image forming apparatus acquires read image data representing an image obtained by reading a test image and including gradation values of pixels. When a density function is defined, which represents the gradation value of each pixel with the position of the pixel with respect to the (y) direction as a parameter in the read image data, in an interval corresponding to the detection image, it can be regarded as a cyclic function. On the basis of convolution operation, the image forming apparatus determines a positional deviation amount from a phase differenceϕ<SB>M</SB>-ϕ<SB>C</SB>between density functions and an original document angular frequency (f). The phase difference between density functions becomes a magnitude corresponding to the amount of positional deviation therebetween, thereby accurately calculating the positional deviation amount through simple convolution operation. COPYRIGHT: (C)2011,JPO&INPIT |
