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03-11-2013, 08:09 PM   #16
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You all know that LCD monitors can produce moire? Changing magnification can fix it.
It most likely will be gone on prints.

03-12-2013, 03:06 AM   #17
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hmmm..... I can see what looks like moire to me on my work monitor but couldn't at home last night (too dark). This is the raw, lightened a bit

03-12-2013, 05:28 AM   #18
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QuoteOriginally posted by LFLee Quote
can you put a red circle where you think there is moire? I don't see any...
Look at the lines on the tail feathers, the Jay feathers are softer than that.

QuoteOriginally posted by Parallax Quote
Moi???? Mess with your head, Norm?
Puhleeeez....
There you go again, that's exactly what i'm talkin about.
03-12-2013, 06:13 AM - 1 Like   #19
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QuoteOriginally posted by normhead Quote
IN an ordinary every day un-expected shot... do I gt brownie points?
No brownie points

There is moiré, color moiré and maze artifact. All 3 effects are different (i.e., they look different and have different causes). If you would need a general term for such effects, it would be sampling artefact, not moiré.

What you see is a "maze artifact" (in a small region where the feather lines join the wing bone or whatever it is). It is caused by false guessing of the demosaicing algorithm and will vary with the raw converter algorithm used. It is an artifact occuring at Nyquist frequency only and becomes invisible when reducing the image size. Therefore, we can deduce that the visible detail in the feather is real, close to Nyquist, and no artefact or moiré pattern (which would have a lower pattern frequency).

Moiré artifacts are low frequency patterns and don't disappear when downscaling the image.

A sensor with a good micro lens array (a near 100% fill factor) only can have color moiré caused by a weak or no Bayer-AA filter. Only cameras with no micro lens array (older medium format digital cameras) have classic moiré (and jagged edges).

BTW, I am surprised the image is this sharp (1/1250s, right?) with the bird being in the air actually


Last edited by falconeye; 03-12-2013 at 06:29 AM.
03-12-2013, 06:36 AM   #20
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QuoteOriginally posted by falconeye Quote
No brownie points

There is moiré, color moiré and maze artifact. All 3 effects are different (i.e., they look different and have different causes). If you would need a general term for such effects, it would be sampling artefact, not moiré.

What you see is a "maze artifact" (in a small region where the feather lines join the wing bone or whatever it is). It is caused by false guessing of the demosaicing algorithm and will vary with the raw converter algorithm used. It is an artifact occuring at Nyquist frequency only and becomes invisible when reducing the image size. Therefore, we can deduce that the visible detail in the feather is real, close to Nyquist, and no artefact or moiré pattern (which would have a lower pattern frequency).

Moiré artifacts are low frequency patterns and don't disappear when downscaling the image.

A sensor with a good micro lens array (a near 100% fill factor) only can have color moiré caused by a weak or no Bayer-AA filter. Only cameras with no micro lens array (older medium format digital cameras) have classic moiré (and jagged edges).

BTW, I am surprised the image is this sharp (1/1250s, right?) with the bird being in the air actually
Darn, I really had my heart set on brownie points...

Yes is is somewhat unusual to get an image that sharp of a moving bird, sometimes the stars just align for you.
03-12-2013, 08:38 AM   #21
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Cool, thx falc. I of course had to google Nyquist but hey, learn a new thing every day . Someone identified this as moiré but I take it that this was wrong and is in fact a maze artifact? The circley wavey patterny things. Happens a lot when I resize down to 2000px from 4900:

03-12-2013, 09:30 AM   #22
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QuoteOriginally posted by Nass Quote
The circley wavey patterny things. Happens a lot when I resize down to 2000px from 4900:
Patterns emerging when downsampling are classical moiré.

This includes watching scaled images (images scaled to fit the screen, a browser area etc.).

They can be somewhat avoided by using "bilnear" as downsampling method (esp. if combined with a 50% scale and subtle pre-blurring) and are maximized by "next neighbor" as method. The popular "bicubic" sits somewhere in between.

The name maze in maze artefact comes from maze, the tour puzzle. It can make photographed parallel lines separated by exactly 1 pixel suddenly change the direction by 90° where the original lines don't. So, an area with parallel lines suddenly looks like a maze. Such an area exists in the bird photograph, but it is a tiny area only (located at the upper boundary of the tail feathers).

Last edited by falconeye; 03-12-2013 at 09:37 AM.
03-12-2013, 09:41 AM   #23
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There's no overlapping or double pattern so it's no moire, it's just fine feather detail. Also, that is not even a sharpening issue, the reason the detail isn't fine the whole feather, the outer part of feathers get more fluffy/frayed/used/etc so the tips are more fine and fuzzy and that is why there is less detail.

03-12-2013, 09:50 AM   #24
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QuoteOriginally posted by joe.penn Quote
There's no overlapping or double pattern so it's no moire, it's just fine feather detail. Also, that is not even a sharpening issue, the reason the detail isn't fine the whole feather, the outer part of feathers get more fluffy/frayed/used/etc so the tips are more fine and fuzzy and that is why there is less detail.
Now who would have thought you could get fine feather detail without a K-5 IIs?
03-12-2013, 09:53 AM   #25
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QuoteOriginally posted by normhead Quote
Now who would have thought you could get fine feather detail without a K-5 IIs?
Haha, priceless

Thanks falc
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