Need advice on building a noise profile

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thtl
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Need advice on building a noise profile

Post by thtl »

I'm trying to build a noise profile for the Olympus E-P3 and need advice on the following:

1. Can/should I use black screen (lens cap on) instead of the calibration chart? I asked because at high ISO the photos I took are invariably burnt out at long exposures;

2. Regardless of whether I used black screen/calibration chart for photos with a lot of noise the auto-profile quality is very low. Is the resulting profile usable? Is there a way to improve the quality?

Thanks in advance for any suggestions.
NITeam
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Post by NITeam »

1. I do not recommend that. It is better to make sure the target is properly exposed (for example using automatic exposure).

2. If you accurately expose the target, the quality should become higher.

Vlad
thtl
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Post by thtl »

Thank you for your response. Looks like I have to get myself a few ND filters for those high ISO/long exposure shots.

At these extremes (high ISO/long exposure) I am not able to expose every square in the calibration target correctly - the lighter (brighter) squares tend to burn out. Is it necessary to get every square exposed correctly?
NITeam
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Post by NITeam »

It is not absolutely necessary, just desirable, in order to make accurate measurements in all squares.

Vlad
thtl
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Joined: Wed Sep 07, 2011 3:19 pm
Location: Hong Kong

Post by thtl »

Another question: if I use A (aperture priority) mode I have no control over shutter speed. It is my understanding that different shutter speed produces different degrees of noise. Would a profile generated using the A mode be applicable to a whole range of shutter speeds? What about hot pixels generated from long exposures?
NITeam
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Post by NITeam »

There may be some difference, different shutter speeds can be profiled separately or you can simply use Auto Fine-Tune function to adjust a pre-built profile (from the set of profiles that you create using shots of the target) to every input image.

Hot pixels are not noise that Neat Image works with and they are best treated by the camera and its software.

Vlad
thtl
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Joined: Wed Sep 07, 2011 3:19 pm
Location: Hong Kong

Post by thtl »

Understood. Thank you for your response and advice.
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