Welcome to the forum my friend.
I think you are referring to a MOIRE pattern.
You may find this advice helpful.
One step in removing the patterns is to use effects like Gaussian Blur. Experiment with the effect radius to minimize the image quality loss (Gaussian Blur just blurs the image resulting in loss of sharpness). You can use not only integer values but also fractional. If the radius of 1 pixel seems to be insufficient but 2 pixels are too much, you can specify 1.5 pixels or thereabouts. Punching up the overall sharpness of the image, Gaussian Blur effect reduces fine jitter and speckles. However it can't heal the image from moirés completely. |
Sometimes, scanning the original rotated to some angle (for example 15°) then rotating it back in an image editing software in conjunction with blur effect may further decrease the affect of moiré patterns.
Obviously the best way to remove the moiré patterns is to avoid scanning a printed originals. Always choose the photographs and slides when possible. Scan magazines and books only if no alternative exists.