HowTo: adjust NI settings when ETTR done?

questions about practical use of Neat Image
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l_d_allan
Posts: 35
Joined: Thu Sep 24, 2009 3:00 pm

HowTo: adjust NI settings when ETTR done?

Post by l_d_allan »

Summary:
I use ETTR (expose to the right) for many outdoor scenics, and I'm unclear whether I should adjust NI settings to take this into account.

Would this be an appropriate situation to use "Presets"?

More Info:
I've been using NR 6.x since late 2009, and have been impressed. Nice product!

I mostly use the default profiles generated from the Batch Profiler and the Calibration Target. They mostly seem to work well. I consider myself a semi-newbie at understanding all the options and settings for NI.

Originally, I used NI mostly for indoor pictures when I used higher ISO.

Lately, I've been taking more scenic panoramas at low iso on a tripod. In this situation, I generally set the exposure according to ETTR guidelines (expose to the right).

This involves:
* have a moderate amount of overexposure
* the histogram curve will have moved to the right compared to a normal, non-ettr exposure
* objective is to improve highlights and reduce noise
* perhaps 1/3rd to full stop of overexposure
* I enable "Highlight Alert" on my Canon DSLR, and increase exposure by 1/3rd stop until I get "blinkies" indicating blown highlights, then back off 1/3rd to 2/3rd stops until "blinkies" stop.
* Alternatively, on a sunny day outside, I base exposure on "sunny 16" and then increase exposure by 1/3 or 2/3 stops. So I might start at ISO 100, f16, and 1/100 second. Then have ETTR by increasing expose to 1/80 or 1/60. This decrease softness from diffraction by changing f-stop to f8 and 1/320 or 1/250.

With ETTR, my experience is that you reduce the exposure in ACR to compensate for the overexposure done when the image was shoot.

It seems like these compensating adjustments would make a difference on the preferred settings for NI. If I understand how NI works, I would think that the image using ETTR should have less noise that an image with non-ETTR exposure. You would want to use less NR. But perhaps I have a flawed understanding of how NI works?

Also, I'm unclear how NI would be able to detect that ETTR is applicable. As far as NI is concerned with CR2/DNG/RAW, it seems that it only "pays attention" to the camera model, and ISO. Resolution and shutter speed don't seem to matter much, and I don't see how to have different values for "Sharpness" (see http://www.neatimage.net/forum/viewtopic.php?t=2222)

Is this a situation where a "Preset" would be appropriate? I haven't used Presets enough to understand how they work, when they are appropriate, and how to use them with batches with a Photoshop CS4 batch action.
NITeam
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Joined: Sat Feb 01, 2003 4:43 pm
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Post by NITeam »

I think it is more important to get the noise profile right than to select preset / adjust the noise filter settings to compensate for a less than perfect noise profile. Therefore, my recommendation is to make sure you build and use the best available noise profile taking into account the fact that you introduce arbitrary adjustments to the image at the ACR stage. To take that into account automatically you have two major methods:

1) build a new noise profile for each input image using Auto Profile; this will automatically take into account any adjustments and there is no need to track them individually;

2) use a good-quality profile set for this camera, load most suitable/matching noise profile for the current input image and additionally Auto Fine-Tune the loaded profile, to automatically compensate for the minor differences in noise properties introduced by those arbitrary adjustments in ACR.

Vlad
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