What is this artifact?

Started Jan 26, 2013 | Questions
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Spazmedia Regular Member • Posts: 173
What is this artifact?

Just got a Sony NEX-6 which I have been enjoying. The image quality is top notch though the menus are terrible. (At least coming from Nikon and Canon).

One odd thing though came out in a picture taken of my daughter. There some strange artifact on the green part of the shirt. Is this moire? Hopefully you can see it from this crop and the image is not being re-sized by dpreview site.



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ANSWER:
uhligfd Senior Member • Posts: 1,855
Re: What is this artifact?

Have a look at the shirt, maybe it is of a ribbed cotton material and that is what you are seeing.

Lightshow
Lightshow Senior Member • Posts: 4,323
Re: What is this artifact?

Yes that's what it is, it happens when fine details and the pixel structure have lines/mm that are close, 1:1 - 2:1

A little local blurring where the effect shows will tone it down, the same effect the alias filter does, or is supposed to do as in this case.

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selected answer This post was selected as the answer by the original poster.
Green_Thark Contributing Member • Posts: 988
Re: What is this artifact?

Was this jpeg or RAW if RAW what did you use to convert?

Looks like the demosaicing has gone a bit squiffy. might just be the thread pattern on the shirt, but I'd keep an eye on it, if you see this pattern often it might be a fault.

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Always keep your words soft and sweet, just in case you have to eat them

Spazmedia OP Regular Member • Posts: 173
Re: What is this artifact?

uhligfd wrote:

Have a look at the shirt, maybe it is of a ribbed cotton material and that is what you are seeing.

That's what I thought at first but its just regular old cotton weave. Thanks anyways for the suggestion.

 Spazmedia's gear list:Spazmedia's gear list
Nikon D100 Canon EOS 7D Sony Alpha NEX-6 Canon EF 50mm f/1.4 USM Canon EF-S 18-200mm f/3.5-5.6 IS +6 more
Spazmedia OP Regular Member • Posts: 173
Re: What is this artifact?

Lightshow wrote:

Yes that's what it is, it happens when fine details and the pixel structure have lines/mm that are close, 1:1 - 2:1

A little local blurring where the effect shows will tone it down, the same effect the alias filter does, or is supposed to do as in this case.

That's surprising (amazing almost!) given I was shooting handheld and the ISO was at 1000. I guess this supposedly not so sharp lens is quite sharp! Thanks for the help.

 Spazmedia's gear list:Spazmedia's gear list
Nikon D100 Canon EOS 7D Sony Alpha NEX-6 Canon EF 50mm f/1.4 USM Canon EF-S 18-200mm f/3.5-5.6 IS +6 more
Spazmedia OP Regular Member • Posts: 173
Re: What is this artifact?

Green_Thark wrote:

Was this jpeg or RAW if RAW what did you use to convert?

Looks like the demosaicing has gone a bit squiffy. might just be the thread pattern on the shirt, but I'd keep an eye on it, if you see this pattern often it might be a fault.

-- hide signature --

Always keep your words soft and sweet, just in case you have to eat them

Shooting JPG. Thanks for the info!

 Spazmedia's gear list:Spazmedia's gear list
Nikon D100 Canon EOS 7D Sony Alpha NEX-6 Canon EF 50mm f/1.4 USM Canon EF-S 18-200mm f/3.5-5.6 IS +6 more
ZhanMInG12
ZhanMInG12 Forum Member • Posts: 56
Re: What is this artifact?

I think that might be the in camera noise reduction at work in an unpleasant way.

Better to shoot raw and then use software to control the amount of reduction

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too lazy for DSLRs:-)

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