Author Topic: Scanner owners help request (Read 3985 times)

Xairbusdriver · « **on:** September 03, 2012, 12:50:47 PM »

I'm trying to figure out if the resolution used to scan an image is the determining factor in the creation of moiré patterns. The scanner in our MFP has an upper limit of 600dpi. Most suggested 'solutions' to eliminating moiré patterning recommend using 150 to 200% of the images final output. With that as a limiting factor, I would be lucky to get good output at 300dpi. But I don't...

Here is small portion of a 600dpi, un-edited scan:

The patterning is caused by the dots laid down by most any printing process used today. The positions of those tiny dots seldom aligns with the receptors in the scanner. Further, the sizes of the receptors usually differer from the dot sizes. The result (even assuming same size dots, which is not always true) is that some receptors will 'see' a whole dot while others will 'see' parts of two (or more) dots or the gaps between them. A single receptor has to interpolate what the 'color' is and this can create false colors in a particularly angled line that basically ruins the copied image.

My request, should you decide to accept it, is to scan the same (newspaper or magazine) image in several distinct resolution setting on your scanner and report the (unencrypted) results. Does a higher resolution setting result in less moiré or simply smaller lines?

BTW, I'd suggest using only the optical resolution settings not the higher, software derived settings.

Other suggestions, links, hardware recommendations are welcome, of course.

Thanks!

note to admin: this post may disappear after anyone reads it.

Raven · « **Reply #1 on:** September 03, 2012, 03:39:56 PM »

XABD,

The higher resolution the better. 1200 dpi would be best.
Turning the original and scanning will reduce the pattern a bit.
Photoshop filters will help by creating a soft focus.

Check out these tips...

http://www.scantips.com/basics06.html
http://www.oberonplace.com/dtp/moire/index.htm

Xairbusdriver · « **Reply #2 on:** September 03, 2012, 03:52:14 PM »

I'll check those links, thanks!

I've even tried taking multiple scans, each at slightly different angles, then combining them with different opacities on each layer. I've also seen suggestions/tutorials using various ways to soften the focus (Noise->Median, Gaussian, etc.). I think the 'solution' is a high resolution (higher than I have on the MFP, anyway) and very high quality images. Even some "photographs" are now actually just prints from an ink-jet printer! And then there are dimpled surface papers that reflect light causing a hybrid moiré pattern!

But with my limited dpi scan function, even old photos that were printed well before the middle of the last century still display this problem.

I probably should invest in a good scanner if I want to pursue this activity. What model/brand are you using?

Later...
Your links:
I've even got that scantips page bookmarked from well over 10 years ago! I recognized it as soon as I saw the image of the motor cycles!

I'm sure it's been updated but I remember going there when I was using a graphics app called ColorIt! Way back in OS 8 & 9!!!

Even the other page was last copyrighted in 2000! Of course, the problem is not new nor are the attempts to correct it. Thanks again!

The scanner function is also maxed out at 600dpi. The printer can print at double that but that doesn't help with scanning stuff. It's just not designed/built as a higher performance scanner, especially for a black & white laser printer. It's really designed for text (for which it's great!) and an occasional grey scale image. Time to search for a dedicated scanner, I suspect... and a place on the desktop(s) to put it!

tacit · « **Reply #3 on:** September 03, 2012, 07:21:15 PM »

You're right on the money that software-interpolated resolution won't help. If the scanner's true optical resolution isn't high enough, there's an old munchkin trick that sometimes works: Stack several layers of clear acetate on the scanner bed, then put the thing you're scanning on top of that. What that does is push the thing you're scanning very slightly out of focus, which will sometimes help reduce moire.

Xairbusdriver · « **Reply #4 on:** September 03, 2012, 09:30:07 PM »

QUOTE

there's an old munchkin trick

I didn't even know they had scanners along the 'Yellow Brick Road!'

That 'trick' seems to be what most 'instructions' recommend, however, not having the wide-spread availability of munchkins, the de-focusing is done after the fact in a graphics editing app. Unfortunately, the evil 'Moiré Eelvil' has already been done by that time.

BTW, is the munchkin use of those layers of acetate part of the reason some scenes were missing from copies of that film?

Raven · « **Reply #5 on:** September 03, 2012, 09:46:30 PM »

You want to start with the best possible scan you can get and then use whatever Photoshop filters you want secondly - Gaussian Blur, Remove noise, despeckle, etc.

I've been using an Epson Perfection 2400 Photo scanner I purchased in... 2003! (Gawd, has it been that long!) It has served my needs well as a professional graphic designer. Originally I would scan colour print photos up to 150% or less. Always at 300 dpi for commercial printing purposes. It does allow me to scan photos up to 1200 dpi. Not many Kodak colour photos around any more since digital cameras. I now use the scanner mostly for scanning line art. The 2400 was only about $250 at the time. It has a transparency attachment which is mediocre at best. Nothing can compare to a dedicated slide and film scanner.

I KNOW there are better flatbed scanners for cheaper today.
Go for it! :-)

Highmac · « **Reply #6 on:** September 04, 2012, 01:03:41 AM »

A roundup of scanner reviews from the MacFormat stable of mags - http://www.techradar.com/reviews/pc-mac/pe...anners/scanners

It's a UK site but hope it helps

Frances144 · « **Reply #7 on:** September 04, 2012, 04:57:53 AM »

Interesting. I have a loathe/hate relationship with my scanner.

Xairbusdriver · « **Reply #8 on:** September 07, 2012, 06:22:54 PM »

So I took your advice and bought an Epson V500. Arrived today. I must say it runs rings around the scanner function of the MF printer!

Just compare this to the previous 600dpi scan!

This one was scanned at 6400dpi

Both are approximately the same portion of the same printed image. The 600dpi scan used none of the extra software functions available (Descreening, Color enhancement, Sharpening, etc.). I tried to make it exactly like the scan in the first post (scanned at 600 dpi, reduced to 300dpi in elements).

The second scan did use the "Magazine" descreening filter but nothing else. Like the other image, I did nothing but reduce the resolution to 300dpi.

Granted, both originals had morié patterning, the 600dpi more than the 6400.

And the 6400dpi took considerably longer to scan. 10.6 times? I think it was more like 100.6!

But simply reducing both originals to 300ppi reduced the moiré pattern to acceptable levels, without any extra steps. Of course, I know this is all illusion, smoke and mirrors; there can't possibly be 6400 sensors to the inch in that scanner!

Now, if I can just get my wife's MBP to actually see and be able to share the thing...

Xairbusdriver · « **Reply #9 on:** September 08, 2012, 01:19:12 PM »

Gave up on sharing the scanner. I just connected the MF printer to her MBP and she can access the scanner in it. The newer one will be connected to my iMac and I'll use it. Neither Mac can use the other one's scanner. Installed several versions of scanner software on both machines, sometimes more than once, I'm just glad she can scan something and print to the both printers!

While PC Nation had a great price, their shipping "manners" leave a bit to wish for. OTOH, nothing seems to have been broken. At least I don't think the Sharing was included in the box...

Xairbusdriver · « **Reply #10 on:** September 10, 2012, 01:50:21 PM »

Attached the scanner to the Airport Extreme. Restarted the iMac, the MBP after resetting the Extreme. Scanner did not appear in either computer. Conclusion: This 'solution" isn't.

The new scanner is back on my iMac, my wife still can access the Multi-Function machine with its less capable but satisfactory scanning capabilities. We both have a scanner, we can print to both printers, life is too short to keep 'hitting' this Sharing 'problem.'

kimmer · « **Reply #11 on:** September 10, 2012, 02:54:06 PM »

Interesting adventure. We long ago gave up on sharing the scanner. If Sneakers needs something scanned, I do it (printer/scanner is USB'd to my machine), and network it to him. He can print, but not scan. Go figure.

Xairbusdriver · « **Reply #12 on:** September 10, 2012, 05:09:19 PM »

QUOTE

We long ago gave up on sharing the scanner

Now you tell me!!!

Same here... now! But she can now scan on the Brother. Of course, she will now want to know why the 600MB image won't fit in the email...

kimmer · « **Reply #13 on:** September 10, 2012, 07:11:32 PM »

QUOTE(Xairbusdriver @ Sep 10 2012, 03:09 PM) <{POST_SNAPBACK}>

QUOTE

We long ago gave up on sharing the scanner

Now you tell me!!!

I know that our network setup here is not "correct"* and so giving you info on sharing something over your network would be skewed. Or maybe I just wanted to watch as you ripped your hair out?

*I used to be able to see Sneakers PPC on the network, but I can't log on to Sneakers iMac even though he can log onto my iMac -- and we can't figure out what setting to fix.

Xairbusdriver · « **Reply #14 on:** September 11, 2012, 07:59:19 AM »

QUOTE

we can't figure out what setting to fix.

Make sure the entry for your Mac has the correct password for your main login account, if you are listed, specifically on his machine. Probably the easiest way would be to delete your entry on his machine and re-enter it.

Of course, you'll have to set your machine up to allow Sharing by listing the directories you want to share in the "Shared Folders: box on your Sharing Pref Panel. If he's not using an Apple OS you might want to check the "Share files and folders using SMB (Windows)" checkbox under the "Options" button. It may be that Linux needs that checked, also.

Finally, it might help to list him, specifically, in the "Users:" list.

News:

Author Topic: Scanner owners help request (Read 3985 times)