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Photography Question 
Ruth Downing
 

What is the best way to deal with moire


Hi,

I have recently encountered my first moire problem whilst taking photographs of a tiled roof property for a client. Please does anyone have any suggestions as to the best way to deal with this problem?


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2/24/2006 8:46:21 AM

 
Mark Feldstein
BetterPhoto Member Since: 3/17/2005
  "Moire problem"?? Well, next time send Moire away while you shoot and that should solve the problem, no?
M.;>)


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2/24/2006 8:22:27 PM

 
David Earls   Hi Ruth,

Are you shooting with film and scanning or are you shooting digital? Does the moire appear on screen or on prints? What image editing software are you using? Could you post a picture that demonstrates this?

There are a few ways you can go after this problem, but we have to know where the moire is being introduced.


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2/25/2006 5:33:46 AM

 
Mark Feldstein
BetterPhoto Member Since: 3/17/2005
  And btw, sometimes ya know, Moire is Leise.
;>)
M


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2/26/2006 3:48:24 PM

 
John G. Clifford Jr
BetterPhoto Member Since: 8/18/2005
  With Bayer-sensor cameras (nearly all digital cameras except for the Sigma SD9/SD10), moire is a result of detail in the image at or beyond the resolution limit of the sensor.

To eliminate moire, make the detail larger. Get closer to your subject. Change the focal length of your lens, either by zooming or by using another lens. Use a higher-res camera, or use a camera with a Foveon sensor. If you can't fit it all in with one photo, take two photos and use panoramic software to blend them into one image.


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2/26/2006 4:12:42 PM

 
Ruth Downing   Thanks for the response to my question - the camera I am using is an EOS 20D with (unfortunately) the 18-55mm kit lens. The only poblems I encounter with my camera occur when using this lens so I guess I need to upgrade it. To be fair, I have never had this problem before and the strange pattern appears both on screen and when printed out. The roof in question has a recurring pattern of blue slate tiles, some of which are covered in moss. From the replies received I understand that this pattern has probably fooled the sensor and I wondered if there is anything I can do in Photoshop CS2 to improve my shot.

Thanks again for the help, much appreciated.

Ruth


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2/28/2006 5:20:13 AM

 
David Earls   Ruth,

I have a 20D and the same lens, but I've not encountered that problem. Nonetheless, there may be things you can do in Photoshop to reduce it.

First, when you open the shot in RGB color, take a look at each of the R, G, and B channels. If the moire appears only on one channel, you can apply some Gaussian blur to that channel only; the blue channel is the one that seems to "attract" noise and patterning than the other two.

Second, if that doesn't work, convert the image to Lab color, then examine each of the L, a, and b channels. If the patterning occurs on the color channels (a and/or b), you can apply Gaussian blur to either or both, then sharpen on the L channel.

The third thing you can try if neither of those approaches works is to find a channel in RGB mode that does not contain the pattern, and then use Image/Apply Image to apply the clear channel to the entire photograph in Overlay or Multiply mode. You'll have to experiment here with which mode works best and with what percentage of overlay/multiply you use.

Sorry I can't be more specific, but we're kind of shooting in the dark here - we haven't seen the image.


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2/28/2006 6:08:15 AM

 
Craig m. Zacarelli
BetterPhoto Member Since: 2/3/2005
  I HAVE A PROB TOO BUT IT SEEMS THE SHARPER THE IMAGE THE WORSE IT IS AND THE SMALLER YOU MAKE THE IMAGE THE WORSE IT IS.. I PRINTED OUT AN 8X10 OF THE PROBLEM SHOT AND THE MOIRE ISNT THERE.. I BELIEVE ITS JUST A DIGITAL TRICK THAT YOUR EYES PLAY ON YOU.
CRAIG-


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2/28/2006 9:58:18 AM

 
Craig m. Zacarelli
BetterPhoto Member Since: 2/3/2005
  I HAVE A PROB TOO BUT IT SEEMS THE SHARPER THE IMAGE THE WORSE IT IS AND THE SMALLER YOU MAKE THE IMAGE THE WORSE IT IS.. I PRINTED OUT AN 8X10 OF THE PROBLEM SHOT AND THE MOIRE ISNT THERE.. I BELIEVE ITS JUST A DIGITAL TRICK THAT YOUR EYES PLAY ON YOU.
CRAIG-


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2/28/2006 9:58:19 AM

 
Ruth Downing   Hi,
The problem Craig has sounds almost identical to the one I encountered, and indeed the image is much worse when sharpened and smaller. The only trouble is that I have to use it small as it is part of a brochure for my client. Thanks David for your help on the technical side, I will try out your suggestions and let you know how I get on.

Thanks again for your help.
Ruth


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3/2/2006 11:48:16 AM

 
Slim Brady 
BetterPhoto Member Since: 3/1/2006
  Its your angle, you might be able to get the shot from a different angle. It happens with certain patterns in clothing also. You might have to shoot from further away.


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3/2/2006 12:23:00 PM

 
Craig m. Zacarelli
BetterPhoto Member Since: 2/3/2005
  Ruth, Im way to lazy and in pain to re-read this whole thread but have you tried printing at the size you are needing this shot to be?
Just curious.
Craig-


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3/3/2006 4:20:05 AM

 
Ruth Downing   Hi Craig,

Yes I have and its awful! I'm just off to try out some of the suggestions - wish me luck!!

Ruth


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3/3/2006 5:18:54 AM

 
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