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Photography Question 
Grant 
 

Distortion of lines on some portraits


I took some important pictures with a Fuji S602 digital and one of the subject's suits had tiny vertical lines in the weave. The results were areas of large swirls and exaggerated appearances. We used Adobe Photo Deluxe 4.0. but did not have very good results. Note that I took these on high resolution 2048 X 1536. Can someone tell me what caused the distortion and what to do about it? I haven't read of others having this problem. Thanks.


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1/16/2003 1:12:43 PM

 
Barefoot Photography by Tina Doane
BetterPhoto Member Since: 1/3/2005
  did you ever fin out what was causing the swirls. Im having similiar problem?


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7/22/2008 10:24:54 PM

 
Barefoot Photography by Tina Doane
BetterPhoto Member Since: 1/3/2005
  did you ever fin out what was causing the swirls. Im having similiar problem?


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7/22/2008 10:24:55 PM

 
Carlton Ward
BetterPhoto Member Since: 12/13/2005
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This is a moire' affect that distorts lines. I also used a Fuji S602 for years and I will even get that effect on occaision with my Canon 40D.
Alan may have the more technical reasoning behind why this occurs but I believe it is simply a transference problem recording an image with fine lines that causes this.
I took an image with this effect that even my eyes were seeing the moire' and was happy my camera was able to record the image the way I saw it. see pic...

But is is usually when you dont want it that you will get the effect.


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7/22/2008 11:07:27 PM

 
Barefoot Photography by Tina Doane
BetterPhoto Member Since: 1/3/2005
 
 
 
Here is a pic where you can see it, I pumped up the saturation really high so you can see it. It is suttle in the printed image but it is there and is driving me carzy. I was thinking something with my lighting, maybe too much light??


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7/22/2008 11:12:52 PM

 
Carlton Ward
BetterPhoto Member Since: 12/13/2005
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  Hi Barefoot, this is looking more like Chromatic Aberation where you get a purple-ish halo effect. Carlton


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7/22/2008 11:37:55 PM

 
Carlton Ward
BetterPhoto Member Since: 12/13/2005
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Chromatic Aberration - http://en.wikipedia.org/wiki/Chromatic_aberration

Moire effect - http://en.wikipedia.org/wiki/Moire_effects


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7/22/2008 11:49:59 PM

 
Alan N. Marcus   Hi Grant,

You have discovered a severe defect that plagues digital photography, television imaging, lithography, as well as a naturally defect of human sight.

It won’t due you any harm to look of the moiré effect.

A moiré effect often occurs when we observe repetitive designs. Drawings that produce optical illusions are often dependent on this phenomenon.

Usually the design is in the shape of a grid however a moiré effect can occur when two irregular patterns are superimposed.

The best example is a common window screen. Often when looking out through the screen you will see light and dark bands and swirls. This is accentuated if you are looking through two screen superimposed.

The heart of the digital camera is the sensor chip that records the image. Its surface is covered with tiny squares (sub-pixels), each filtered with strong red, green, and blue filters. The layout of the pattern of these squares is complex. The layout used by all is the design of Dr. Bryce E. Bayer of Eastman Kodak. The design calls for 50% green, 25% blue and 25% red. This year (2008) Dr. Bayer introduced a new design that will revolutionize the digital camera by increasing the ISO many folds.

Nevertheless, the moiré effect you have discovered is caused by a clash between the pattern of the weave in clothing and the pattern of the Bayer filter arrangement.

Alan Marcus (marginal technical gobbledygook)
ammarcus@eathlink.net


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7/23/2008 8:39:20 AM

 
Carlton Ward
BetterPhoto Member Since: 12/13/2005
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  Thank you Alan, you are a great resource for us all here at BP.
Carlton


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7/23/2008 6:25:25 PM

 
Barefoot Photography by Tina Doane
BetterPhoto Member Since: 1/3/2005
  I understand what it is now but now that it is in my images of this little girl how do I get rid of it in PS


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7/24/2008 11:26:18 AM

 
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