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Author Topic: C1 Purple Fringing / Defringe  (Read 732 times)

JaapD

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C1 Purple Fringing / Defringe
« on: December 13, 2018, 02:05:42 pm »

Gents,is there any reason NOT to set the Defringe value at 100% by default, so without even looking on image by image basis if defringing is actually required?

I did some experiments and found no negative contributions, only positive. However C1 defaults at 0% so I may be missing a good reason here.

I’m interested what your ideas are on this subject. Maybe Doug or David can jump in here as well.

Thanks in advance,
Jaap.
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Bart_van_der_Wolf

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Re: C1 Purple Fringing / Defringe
« Reply #1 on: December 13, 2018, 08:21:47 pm »

Gents,is there any reason NOT to set the Defringe value at 100% by default, so without even looking on image by image basis if defringing is actually required?

I did some experiments and found no negative contributions, only positive. However C1 defaults at 0% so I may be missing a good reason here.

Iím interested what your ideas are on this subject. Maybe Doug or David can jump in here as well.

Don't know, my lenses, with C1 demosaicing and a default C1 profile for my cameras (with AA-filter), and CA correction, do not leave much fringing (if any) to address. So I have not felt the need to test this in depth. I could imagine that there is a risk of desaturating Purples/Blues in parts of the image that should be left alone, when using the Defringe control.

Fringing is often a result of overexposure at higher contrast edges that results in clipping behavior in 1 or 2 channels, but there may be other causes.

Cheers,
Bart
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johnvanatta

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Re: C1 Purple Fringing / Defringe
« Reply #2 on: December 14, 2018, 04:44:58 am »

It can definitely alter details on things that are actually purple. Whether you want to default to it on, and turn it down for purple subjects (which are generally rare) or apply it as needed is your call. I'd hesitate to default on for anything except pure nature or wildlife photography, where true purples are rarest, since when in doubt I'd rather not move sliders.

I've found for some problem images 100% purple fringing on the slider isn't enough, and I have to hit it with selective color anyway.
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Dinarius

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Re: C1 Purple Fringing / Defringe
« Reply #3 on: December 18, 2018, 07:46:38 am »

Fringing is often a result of overexposure at higher contrast edges that results in clipping behavior in 1 or 2 channels, but there may be other causes.

Cheers,
Bart

Bart, my experience exactly. Occurs regularly when shooting against a cloudy (and, therefore, bright) sky, whereas it doesn't against a blue sky.

Also, lens-dependent to some extent. My Canon 45mm T/S is a particular culprit.

D.
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TomRobbins

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Re: C1 Purple Fringing / Defringe
« Reply #4 on: December 18, 2018, 03:59:42 pm »

Bart, my experience exactly. Occurs regularly when shooting against a cloudy (and, therefore, bright) sky, whereas it doesn't against a blue sky.

Also, lens-dependent to some extent. My Canon 45mm T/S is a particular culprit.

D.

I noticed the same with my copy of the 45mm, Dinarius. This is much improved with the 50mm version, however.
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Dinarius

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Re: C1 Purple Fringing / Defringe
« Reply #5 on: December 19, 2018, 04:17:05 am »

I noticed the same with my copy of the 45mm, Dinarius. This is much improved with the 50mm version, however.

Thanks.

TBH, I think that 50mm was a very strange choice for a T/S. 45mm is excellent, a switch to 40mm would have been ideal.

D.
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