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Author Topic: Confusion Over Options For RAW Image Processing  (Read 7055 times)
Slobodan Blagojevic
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« Reply #40 on: March 01, 2011, 11:00:00 AM »
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... When using ACR on images with 1SO 200 - in effect no noise - and I raise saturation I find that I have to be careful when raising the blue saturation, especially in skies. The effect looks very much like posterization.

I hate to repeat myself, but isn't it the case of an imperfect screen/preview rendering? Meaning that if you export the image, at the same stage where you can clearly see noise/posterization, as a tiff file and open it in PS, the artifacts would not be there?
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John R Smith
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« Reply #41 on: March 01, 2011, 12:22:30 PM »
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I hate to repeat myself, but isn't it the case of an imperfect screen/preview rendering? Meaning that if you export the image, at the same stage where you can clearly see noise/posterization, as a tiff file and open it in PS, the artifacts would not be there?

The artefacts I am discussing are clearly still there once a 16-bit TIFF has been exported to PS. I zero the colour noise slider from its default of 25 before I start work on a file, because I want to carefully monitor any problems of this sort as I go along. I do my sharpening and noise reduction as the very last step in the process, before I export a TIFF or make a print. In B/W we tend to make pretty severe adjustments and manipulation of the image, probably more than one would in colour, at least to the luminance values. As in the wet darkroom, the "negative" is just the starting point. And all of these adjustments can lead to unexpected image degredation and unwanted aretefacts, but often only in a relatively small part of the picture. Because these artefacts can only be seen at 100% in LR (as with sharpening and NR), with big files like my 39MP ones, it is very difficult to keep track of what is going on, because you can only see a tiny part of the image at any one time at 100%.

Admittedly, with my 3FR files you won't see a problem in a 10x8 print. But if you print a big one you will see them alright. And our aim should always be to produce the best possible quality, surely?

John
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Slobodan Blagojevic
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« Reply #42 on: March 01, 2011, 12:41:38 PM »
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... I zero the colour noise slider from its default of 25 before I start work on a file...

Imho, that might be a serious mistake. Jeff Schewe will correct me if I am wrong, but there must be a reason the default is set as 25, even if the luminosity default is zero. Every raw file needs some amount of color noise reduction. By not reducing/eliminating it, you are exposing the color noise to amplification by b&w conversion. And as noise tends to be most pronounced in the blue channel, that is why you see it mostly in the blue sky. Again, imho.
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John R Smith
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« Reply #43 on: March 01, 2011, 01:05:30 PM »
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Imho, that might be a serious mistake. Jeff Schewe will correct me if I am wrong, but there must be a reason the default is set as 25, even if the luminosity default is zero. Every raw file needs some amount of color noise reduction. By not reducing/eliminating it, you are exposing the color noise to amplification by b&w conversion. And as noise tends to be most pronounced in the blue channel, that is why you see it mostly in the blue sky. Again, imho.

Slobodan

Now I am wishing I had just kept my big mouth shut and not made my first post. I was just trying to be helpful, honest . . . All I can say is, as I understand it, that NR can be applied at any stage in LR without compromising the end result. It is a parametric editor, right? All that happens is that when you export to TIFF or send to print, the app applies all the adjustments made to the image in one go, as a series of instructions. The order in which you make the adjustments has no bearing whatsoever on the final result. In many cases my Hass files need zero NR whatsover. If I shoot at 50 or 100 ISO and convert to B/W using moderate colour adjustments very often there is no visible noise anywhere in the image, or at most I need 5-10 colour NR to completely smooth things. I would usually regard 25 as overkill.

John
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Slobodan Blagojevic
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« Reply #44 on: March 01, 2011, 01:37:26 PM »
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...The order in which you make the adjustments has no bearing whatsoever on the final result...

Agreed. I was commenting under assumption that you, for whatever reason, refuse to apply any noise reduction.

And, of course, I have not perceived your posts as anything else but "trying to be helpful".
« Last Edit: March 01, 2011, 02:07:49 PM by Slobodan Blagojevic » Logged

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DeeJay
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« Reply #45 on: March 02, 2011, 10:35:15 AM »
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Depending on what system you are using I find for RAW processing that the software the camera came with is the best to use for high quality RAW processing.

I used to work with Canon and think the results from DPP are better than lightroom/ACR. It's a clunky and frustrating program but I found the results superior in colour and tonal rendering.

Also, why Lightroom can't just give RGB colour curves like in photoshop is beyond me.

I do use Lightroom for editing and cataloguing though.

« Last Edit: March 02, 2011, 10:36:56 AM by DeeJay » Logged
Phil Indeblanc
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« Reply #46 on: March 02, 2011, 03:45:05 PM »
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I have been using ACR, I still can't get past the database building of LR, and prefer C1 if not other reasons, just for that. But I notice if you convert ACR to Greyscale, you lose the ability for a plugin when it's greyscale vs RGB. So you have to convert back. Wonder if there is any issues doing this, or if there is a preferred method, as I like using the color saturation and luminosity sliders in ACR before I PS it as I sometimes apply a SilvFX or other plug. Also when using color sliders in ACR with a raw file, I would think the data is used more like Channels tab as it would pull the info from the same source..no?  Thoughts?..
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