Removing Moire from scanned images

[Isedo]

Hi, I'm looking for some def technique to get rid of that moire effect in scanned images. How do you solve this kind of problems?

Suppose to have 10 images to work ok, which is the better way to preserve the sharpnes on them and get rid of the moire?
All filters do some kinda of smoothink and this is very bad looking.

Any true idea that works please?
Many thanks for any kind answer,

Martin

Attached an exemple of the scanned image

[unimatrix001]

It looks more like a texture on the paper you could try the FFT action or image analyzer. either of these would help remove the texture from the scanned photo

[Isedo]

Thanks my friend, can u explain what you mean with FFT and image analyzer?
Thanks

[mistermonday]

Martin, the pattern you refer to is not Moire. The quality of your attachment is blurred and makes it difficult to tell but the pattern is either texture of the media you have scanned / photographed or it is the ink dot pattern from printing press / process.
An FFT silter such as Image Analyzer can be used to filter out repetitive patterns such as these. However, I find that FFT results in a blurred image. You would like get the same result using a noise filter like Noiseware / Noise Ninja / Neat Image which are faster to use than a FFT filter. In my opinion you will never be able to get a high quality result when after you filter or blur the pattern away. However, you may obtain a result which is satisfactory for some purposes. Depends on the intended use of the resulting image.
Regards, Murray

[Isedo]

Thanks for your kind reply!

Can you explain please how to use some of that filters to try to filter this texture away? I have noise ninja on my Photoshop installed.

Many thanks,
Martin

[unimatrix001]

you can download Image analyzer from this link
http://download.cnet.com/Image-Analy...-10429018.html
and you can get the fft filter and action from this link.
http://www.3d4x.ch/index.php?xml=Swi...+Alex+Chirokov

[Isedo]

Thanks, trying the fft.

See ya soon and thanks again for helping

[Markzebra]

These are halftone dot patterns. Best thing is to deal with each channel separately, use the median filter with low values designed to just 'block' the pattern on each. Very low radius blur can then be used, and then edge detail can be retrieved with Unsharp mask. It will never be perfect because fine detail is basically screwed in files like this, but its the best method you will find.

Commercial 'ant-moire' filters can do nothing more than this, and in fact will just take away the control that you have over each part of the process.

[JohnHarris]

Our preferred method for dealing with scans of halftones:

• Scan at 1200 ppi or better with a slight rotation of the art on the flatbed or on the drum. 3 or 4 degrees is enough.
• Work the file by applying median or blurring to soften the dots just to the point of merging - in other words, they blend together and you no longer see a dot. If you prefer to do this in individual color channels, be careful that you do not introduce color fringing. This can occur if you use distinctly differing blur/median settings on the channels.
• Add hi-pass sharpening at this higher resolution and flatten.
• Add a little noise - around a level 2 or three. This will add some "tooth" for the next step.
• Decimate (downsize) the image to your final resolution. The noise in the previous step helps to dither-out artifacts.
• Hi-pass sharpen to taste at the new resolution. You may need to despeckle the hi-pass layer to minimize artifacting in smooth areas.
• Flatten and save.

[Isedo]

JohnHarris great tips! Thanks a lot!

[phisean]

One additional point to add to Johns, differential blurring: Apply the median blurring on a per-channel basis, blue is noiser than green which is noiser that red, so say you needed a radius of 1 on red this could be 2 on green and 4 on blue.