| 摘要 |
PROBLEM TO BE SOLVED: To read an image by using a picture element density around a dirt area so as to interpolate density data of an image of the dirt area on an original through a reflected light from the original thereby surely eliminating the dirt of a multi-value image. SOLUTION: A high pass filter eliminates a low frequency fluctuation component of data of a linear image 41 with respect to its X coordinate stored in an image memory 38, and a low frequency elimination linear image in which y-coordinates of dirt part 42 corresponding to a dirt are set higher and y- coordinates of parts without dirt are set lower is obtained. Then the y- coordinates of a low frequency elimination linear image 43 representing detection of the dirt area are binarized by a prescribed threshold level ys and x- coordinates x1, x2 corresponding to both ends of a part larger than the ys are detected. Then a laser light source 10 is turned off and a fluorescent lamp 11 is turned on and an original emission slit light being a white light is emitted in the subscanning direction of an original 3. Then the linear image of the slit light is formed on a CCD 17. Thus, the dirt is surely eliminated and the resulting image is read. |
