image pattern

[thanhnhat]

I have a question for all of the expert in here. How do I handle heavy image pattern. The best example would be those images scanning from magazines and books. They are half tone printed so when it is scanned again, it created dots all over the place. I called these as pattern. Please advise me if you have the answer to this. I am working on my PhotoShop skill and quite sometime I encounter this problem. Thank you very much and have a wonder NEW YEAR of CELEBRATION.

[Axleuk]

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.

[DannyRaphael]

I found a couple tidbits on the net that describe various ways of addressing moire. These look promising and should get you moving...

http://graphicssoft.about.com/od/glossary/l/blmoire.htm
http://graphicssoft.about.com/cs/pho...emovemoire.htm
http://www.thefab.net/scanhints/moire.htm (courtesy of Stephen M. Caution: This is an x-rated site that also has some pretty good Photoshop tutorials)
http://www.shootsmarter.com/infocenter/sa016.html Note: registration required

[Duv]

You could try using noise reduction software. Here's a before and after using Grain Surgery. Probably the best is to paint over the image using the Blur Tool set at about 10% Opacity.

Cheers
Dave

[krishna]

If you are referring to Halftone patterns, I would suggest the method of editing the Fourier Transform of the picture. An excellent example (though not halftone, the principle is the same) can be found at http://retouchpro.com/forums/showthread.php?t=9373. Flora has done a very good job of a picture printed in patterned paper.