To properly remove a moire stripe while suppressing deterioration of original components by automatically detecting the number of printing lines or an angle.

This device is provided with a picture inputting part 10 for fetching the two-dimensional picture information of an original, frequency characteristic distribution extracting part 22 for extracting two-dimensional frequency characteristic distribution, polar coordinate converting part 24 for converting the two-dimensional frequency characteristic distribution into signal intensity distribution expressed with polar coordinates, estimated number of printing lines and angle calculating part 26 for calculating the estimated number of printing lines and an estimated printing angle, and picture processing part 16 for conducting processing on the picture information based on the estimated number of printing lines and the angle. The signal intensity dots are distributed in a dot angular direction in the two-dimensional frequency characteristic distribution, and the peak position is generated at a position equivalent to the number of printing lines, and the peak position is converted into a polar coordinate so that the estimated number of printing line and the angle can be obtained.