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Photo Restoration Repairing damaged photos

Digital Camera Moire

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  #1  
Old 11-28-2002, 11:14 AM
christo christo is offline
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Digital Camera Moire

I work for a small real estate newspaper and lately the majority of images we have received from Agents have been unretouched jpeg files from digital cameras. In many of them we are seeing a distinct moiré pattern, usually where the repeated geometric patterns in the design of the house exist. Typically this is usually the roof tiles, or siding of the house. I have tried to remove the moiré in PhotoShop 6 using the filter>noise>deskpeckle, the filter>blur>gaussian blur and the filter>noise>median, and Katrin Eismann's LAB method all with limited and unsatisfactory results. I did purchase Quantum Mechanic Pro, but was profoundly disappointed with it. I also purchased Grain Surgery, and while I am still experimenting with it, (it does show some promise), I have yet to find a way to remove the moiré, without sacrificing sharpness.
Any suggestions?
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File Type: jpg spensecrst141.jpg (39.8 KB, 121 views)
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Old 11-28-2002, 12:07 PM
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gland gland is offline
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Added a new layer and air brushed in a couple different colors of grey on the siding and added a little noise.

A bigger picture would be better to work with.
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File Type: jpg morie1.jpg (15.1 KB, 86 views)
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  #3  
Old 11-28-2002, 04:14 PM
Stephen M Stephen M is offline
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I agree.

A crop of the full res data would be better.

Was the original image full colour?

Fixing luminosity damage is harder than hue/chroma damage.

So the QM moire eraser tool did not work well.

Perhaps look at methods in this link:

http://members.ozemail.com.au/~binar...V_links.html#G

I don't think this will help - but it may, but it may be worth a look. Perhaps write to Fred and ask to send a hi res crop sample or two for him to send you back as corrected samples as a demo before purchase.

http://www.fredmiranda.com/MR/index.html

Stephen Marsh.
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Old 11-28-2002, 09:48 PM
christo christo is offline
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I found the original image, but it is too large to be sent here. It can be seen at http://home.teleport.com/~christo/webpic/SPENSER.jpg. The original was 300 dpi and 5.5 MB in size (5.33x4.00 inches). When I first looked at the image on the screen, I did not see any moiré pattern. I resized the image to fit the ad, did some minor retouching and converted it to a bitmap for use in a BW publication. When the image printed the problem became evident. I went back to the original image and checked it again, and found that the moiré was only apparent when viewed on the screen at a 33% and 66% reduction. I thought this was simply a monitor problem not an image one.
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Old 11-29-2002, 12:32 AM
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d_kendal d_kendal is offline
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Hi Christo,

the problem doesn't seem to have originated from the digital camera photo, but from the retouching. It could be a resizing problem, since when I viewed the full size version in my browser (Opera 6) and used the zoom feature to go down to 20 % (so it would be approximately the same size as the one you first posted) I saw exactly that moire effect. I opened the full size photo in Photoshop 7, resized it to 230 x 172 (the first one you posted was 230 x 173 and thats the closest I could get without changing proportions) then used "Desaturate" to convert it to B&W then saved as a maximum quality Jpeg (at that size, the file was only about 38 k) the end result is attached. Hope that helps you!

- David

P.S. there was a period on the end of the link, that's why it didn't work, here's a fixed link: http://home.teleport.com/~christo/webpic/SPENSER.jpg
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File Type: jpg spenser-moire-dk.jpg (48.3 KB, 44 views)
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  #6  
Old 11-29-2002, 03:55 AM
Stephen M Stephen M is offline
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http://members.ozemail.com.au/~binar...V_links.html#M (scroll down a bit)

Above is a link to a couple of links on moire which I forgot to post before.

In the display and resize thing - I totally agree.

Monitor display can cuase moire between the view magnification and the monitor. 100% view is safest, 50% being OK but can still have small problems due to interpolation and non even weird sizes that are a real problem.

On the resize issue, try different methods of resizing:

* Single resize step

* 66% or 33% reductions to near target size then single step to polish things off

* 10% or other smaller increments to near size etc...

During shooting it can be wise to consider the subjects patterns and if they interfere with the sensor array in the camera...and then to angle the subject or the capture to avoid the issue (try 30 degrees to start with as an approx measure).

Once an image has been resized to final print size/resolution in Photoshop, then examine at 100% view and or perhaps 50%. Although you can get away with resizing the image output slightly in other software or at print, in cases of moire or patterns it is usually safest to swap this convenience for a safer approch.

Stephen Marsh.
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Old 11-29-2002, 07:13 AM
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gland gland is offline
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I totally agree with Stephen and David. The original photo looks great.

My solution was a one step re-size that looks good on my machine. The original photo was 200 ppi so I reset that to 72 ppi and resized to 230x172 in one step.
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Old 11-29-2002, 09:30 AM
christo christo is offline
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As I understand it, what you are all saying is that the image is fine, and that the problem lies in the resizing or methodology we use to convert the image to BW format for publication. Our normal procedure is to take the color image, and resize it to fit the ad, in this case 3 x 2, leaving the resolution at 300 dpi. Image>image size>3 x 2. We then convert it to grayscale using the image>mode>grayscale. In grayscale we adjust the image so that the K dot range runs between 3-85%. The technique here varies with the image, but in most cases we use the eyedropper tool in image>adjust levels, which has been preset with the K dot range. We then do an unsharp mask at 200/1/15. Finally an image>mode>bitmap to the values already mentioned. When I do this on the original, I get the same moiré effect.
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Old 11-29-2002, 10:51 AM
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docilebob docilebob is offline
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I tried it this way and it seemed to work ok. ( at least on screen)

If you gaussian blur the original size at 1.5 pixels, and then resize, the reduction sharpens the blur out ( mostly) then do the unsharp mask to bring the edges back. Then do the levels adjustment, and convert to bitmap.
I`m assuming that your printer needs the bitmap at 200 dpi ?
If not, the jpg works better. Also, if you use desaturate instead of grayscale, you get millions of shades of grey. Greyscale limits you to 256 shades.
Hope this helps.

You may fiind this helpful, too.

http://development.gurusnetwork.com/kpt/tip/10/
( this is aimed at scanner moire, but the tips can be used on digital images, as well )

The Gurus Network has resurected Kai`s Power Tips. Good stuff all around...
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  #10  
Old 11-29-2002, 08:52 PM
Stephen M Stephen M is offline
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Christo - I take it that you ARE saying that as the final point in the files life you use the image/mode/bitmap - command??? What type of bitmap conversion - halftone pattern etc?

I was not aware of this from your previous post/s. I thought that the output was to press, I did not even consider inkjet or laser printers...

I have ALWAYS got MUCH better results by placing a TRUE contone grayscale image into Xpress or PageMaker and using the native function of the layout software to halftone screen an image - rather than making the image bitmap with a preset halftone in Photoshop (presuming PostScript mono laser or colour copier type output).

In almost all cases where a screen is required at output - this is best handled in other software such as a RIP or with the print engine at output time, with the source file being continuous tone (gray/rgb/lab/cmyk and not bitmap).

Unless you view a prehalftoned image (bitmap halftone or whatever) at 100% or 1:1 or 200% or higher - you will get interpolation artifacts...even at 50% view this will happen, just not as bad as at other sizes.

Stephen Marsh.
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