descreen filter?

#1
I have gotten a few scans from others who do not have a 'descreen' function on their scanning software - or didn't use it. This has left a kind of Moire pattern on the pictures and I was wondering how to get rid of it. Thanks.
 
#2
This is inevitably destructive as you have to change the original material.
But if they cannot be rescanned, the best way in is the channels palette.
Take a look at every channel separately andyou will probably notice that one of them is more affected than the others. This reduces the problem to one third/one fourth, and also has the advantage of having the other channels available.

A lot of people blur this affected channel a little bit, but an edge mask to protect the edges against blurring gives better results.
 
#3
origanl scans

Well, I am so inept with Photoshop that I don't quite know what you want done with the channels.

When I look at the channels for the b/w one, there is only one. It is a newspaper clipping.

The color one seems to have one channel that looks fairly good - the red one. Note the coloring of the jacket.

I was just hoping I had missed a 'descreen filter' somehow. I know this works well when I choose that option on my scanner, but I don't know how it works - something about lines per inch. So the best bet will be to ask that they be rescanned with a descreen function.

Thanks for your help, I know this is rather 'common' - no art here...
 
#4
That is indeed the best solution because your scanner can work directly from the original material, and Photoshop is limited to what was scanned.

In case the moir? patterns are difficult to remove, and this is often the case, you can always try changing the angle (I mean: align the photo the scannerwindow's edge, and then turn it slightly.) For a greyscale (black and white) image, try 15?, for a dark coloured one 15, and a lighter one 45?.

A second thing you can do when scanning screened images is scan at a very high resolution. ( at least 600spi (samples per inch))

A third thing is to always scan in RGB mode (colour mode) because it does give you more options.

I just remembered that I once found a Photoshop action somewhere on the net that should be useable as a descreen filter. I add it here.

Hope this helps as this is a tough problem, most certainly because it needs a sound basic knowledge of PS.

To know how to use an action, check out this thread

In case you run into difficulties, just say so and we will see what we can do.

(May I suggest to read the help files in Photoshop? If you're so lucky as to have Acrobat (not Acrobat Reader) or know someone who does: Acrobat has an option to turn the complete set of html pages into a pdf which is printable) The Help files are a hidden treasure, and in fact a very readable and thorough free book on PS.)
 
#5
Oh goody another Action - thanks Erik:perfect:
 
#6
>I have no idea how to remove half-tone dots from the scan printed image, as
>I want this image to re-print.
>
>I heard there are some techniques and also filters available in Adobe
>Photoshop to remove the half-tone dots from the printed scan images.
>
>Someone suggested me to use the Descreen filter method, but I don't know
>where it is available in Adobe Photoshop?
>
>Awaiting your communication in this matter & thanking you.
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