How do I remove 'dots' (Moire) from scanned images? — OZONE Asylum, home of the Mad Scientists

FAQ

How do I remove 'dots' (Moire) from scanned images?

This page's ID: 5289

You are editing "How do I remove 'dots' (Moire) from scanned images?"

Who can edit an FAQ?	Anyone registered may edit an FAQ.

Your User Name:
Your Password:
Login Options:	Remember Me On This Computer

Your Text: Insert Slimies » Insert UBB Code » Close Last Tag \| All Tags UBB Help	Hello. Something I can't figured out in PS is improving scanned images. What bugs me in this images aret he dots. How can you get rid of them and/or what would you advise to improve scanned images? "Moiré ©s the word for that effect" "If I'm not mistaken, an old trick is to scan it at a 45degree angle and then rotate the canvas in PS back to where it should be. I've heard that helps with moire." Now here's the motherload!! The proper angle would be 15° degs, cyan in generally the most common primary. Black 45° in most cases is so slight that the morie has little effect. But you would want to angle the scan to match most noticable primary. Generally halftone screen angles are at the following. Cyan 15°, Magenta 75°, Yellow 0°, and Black 45°. Printers use what is called, LPI or "lines per inch" do describe the halftone dot size. Generally between 120 -150lpi for normal paper, 65-85 for newsprint, and 175+ lpi for highquality on glossy stock. Basicly you need to scan at as ppi of less then the lpi to eliminate the dot on the scan. or choose to scan holding the dot where by you should try 2-3 times the lpi. ( I can rember the proper value) Some scanners have a descreen function, my scanner it is hidden under an extended menu. Check your software. The method I use for morie' removal in textiles or prescreened originals is: Scanning at 4 times the resolution, switch to LAB mode, there slightly blur the a & b channels and run noise-->median on the lightness channel and then scale down to your desired image size. Then apply a slight usm to the lightness channel. Thou this may bring the pattern back so take care. Then switch back to RGB or CYMK. Resizing steps also helps, forces photoshop to interpolate the colors more then once. Adding slight noise or blurs between moves also may help. This will degrade and or soften the image but the results are often better then a morie'. jstaurtj -------------------------------- Relevant threads: [url=http://www.ozoneasylum.com/Archives/Archive-000004/HTML/20001001-3-000206.html]Newton ring removal[/url] [url=http://www.ozoneasylum.com/Archives/Archive-000004/HTML/20011010-3-001628.html]out, out, evil dots!![/url] [url=http://www.ozoneasylum.com/Archives/Archive-000004/HTML/20011029-3-001687.html]moire no more![/url] [url=http://www.ozoneasylum.com/Archives/Archive-000004/HTML/20020304-3-001992.html]Got Moire?[/url] [url=http://www.ozoneasylum.com/Forum3/HTML/002782.html]Improving scanned images[/url] -------------------------------- Relevant links: [url=http://w3.cablespeed.com/~halmich/tech-slop/amp/]AMP[/url] - warjournal's impressively technical piece on moire removal. ________________________ [small][i](Added by: [url=http://www.ozoneasylum.com/cgi-bin/ubbmisc.cgi?action=getbio&UserName=NoJive]NoJive [/url] on Sat 14-Sep-2002)[/i][/small] [small][i](Edited by: [url=http://www.ozoneasylum.com/cgi-bin/ubbmisc.cgi?action=getbio&UserName=Emperor]Emperor [/url] on Sat 14-Sep-2002)[/i][/small] [small][i](Edited by: [url=http://www.ozoneasylum.com/cgi-bin/ubbmisc.cgi?action=getbio&UserName=jstuartj]jstuartj [/url] on Sat 12-Oct-2002)[/i][/small] Loading...
Options:	Enable Slimies Enable Linkwords

« Backwards — Onwards »

Show Forum Drop Down Menu