Abstract: Methods and apparatus for avoiding moire occurring in color scanning for graphic art, wherein light rays from a color original are passed through a pick-up lens, and prior to starting the color scanning, are modulated by means of a low-pass filter, which modulated rays are branched into two optical paths, on one of the paths a lattice plane is provided so as to project the modulated rays thereon, the lattice plane being beforehand selected in accordance with various conditions for scanning. A possible moire on the lattice plane is observed thereby to adjust the low-pass filter by replacement or displacement until the moire disappears on the lattice plane. Finally the light rays from the color original are modulated by the selected low-pass filter.