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DPChallenge Forums >> Hardware and Software >> what causes moire?
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 03/16/2014 12:06:52 PM · #1
Just did a shoot and half my images have extreme moire!!!! I haven't done anything different, no unusual settings or lighting. And it couldn't have happened to a worse shoot, but that's another story. I've found a way to reduce it almost completely through editing, but I'd like to prevent it from happening again.
 03/16/2014 12:11:43 PM · #2
Maybe this will help...

//www.nikonusa.com/en/Learn-And-Explore/Article/gy43mjgu/moir%C3%A9-false-color.html
 03/16/2014 12:14:22 PM · #3
It's usually caused by having a subject with fine parallel lines (like canvas) -- when lined up against the array of detectors on the sensor you can get interference patterns. Sometimes tilting the camera slightly, moving closer or farther, or slightly de-focussing will help.

You can create moire by layering a couple of pieces of fine mesh (window screen might work, stockings/pantyhose, etc.) stretched out so the lines are in a rectangular grid, and then mis-aligning them slightly.

Message edited by author 2014-03-16 12:38:37.
 03/16/2014 12:41:03 PM · #4
Originally posted by Kelli:
Maybe this will help...

//www.nikonusa.com/en/Learn-And-Explore/Article/gy43mjgu/moir%C3%A9-false-color.html


Sounds like the "prevent it from happening again" could constitute a shiny new D800?
 03/16/2014 12:43:30 PM · #5
Originally posted by aliqui:
Originally posted by Kelli:
Maybe this will help...

//www.nikonusa.com/en/Learn-And-Explore/Article/gy43mjgu/moir%C3%A9-false-color.html


Sounds like the "prevent it from happening again" could constitute a shiny new D800?


Apparently, the D800E causes moire...

Paul, I know why we see moire, just wondering why I suddenly see it so prominently in these shots. It's not unusual material, or particularly fine or anything. It's just so odd.
 03/16/2014 12:47:13 PM · #6
Originally posted by tanguera:
Apparently, the D800E causes moire...

Nah, it just doesn't have the anti-aliasing filter that CORRECTS it: you have to correct in post.

Show us an image with moire from your shoot?
03/16/2014 12:57:09 PM · #7
I'm obsessed with Moirè because it can kill a video shoot, much more than a photo. IMO Nikon did a stupid move with D800E - video shoots don't need more sharpness than a photo. Anyways, there are plenty of ways to fix moiré - search them on the net Johanna :)
 03/16/2014 06:40:43 PM · #8


So, the moire does not seem to be as apparent in LR, but when I import it to PS it REALLY brings it out.
 03/16/2014 08:00:28 PM · #9
Did it appear anywhere other than that fabric? Maybe there is something specific about the knit. It's not in two layers is it?
 03/16/2014 09:42:18 PM · #10
Originally posted by tanguera:


So, the moire does not seem to be as apparent in LR, but when I import it to PS it REALLY brings it out.


I would say that the moire is coming from the fabric. The pattern of the fabric is going vertically and coincides with the direction of the pixels of your sensor (assuming the image wasn't rotated). If you rotate the camera a few degrees (15-20) the moire should change considerably and change direction.

Most likely, what is happening here is that the pattern of the fabric very closely match the sensor pattern, this similarities give raise to the moire effect if you make the patterns more dissimilar the moire will go away.
Look at this 100% crop of your image and the plot of the intensity along the horizontal axis. The zigzag line means that every couple pixels the intensity (pixel value) goes up and down. This change is likely coming from the fabric texture that projected onto the sensor, which means that both patterns (sensor pixels and fabric) are very similar in size.





I think that in this case lighting is also having an effect since the regions with better contrast have less moire. compare the neck line with the middle of the back. Check this crop of the neck region and compare with the previous one.





In this crops there might some extra effect coming from the jpg compression/interpolation, that should be absent in the raw file.
 03/16/2014 10:58:19 PM · #11
Yes, it seems the issue is a combination of the fabric, as it is a tight weave with a definite vertical pattern, the lighting, and the model (who was at the maximum size for the item). I've found a work-around fix, but I believe the result is inferior for the ultimate use of the images, and need to discuss this with the client. A first time for everything, I guess....

Thank you all.
 03/16/2014 11:58:47 PM · #12
I managed a clean fix using Camera Raw's Moire Tool and the brush... Pretty easy.
 03/17/2014 01:46:07 AM · #13
LR also has a moire tool and yes, it's quite good, but not good enough for the intended use.
 03/17/2014 02:23:33 AM · #14
Originally posted by tanguera:
LR also has a moire tool and yes, it's quite good, but not good enough for the intended use.


How about using Viveza to pick the blue (with a large control point) and then sliding the hue to match the pink...
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