Noise Reduction

[William Dickson]

Can anyone tell me the best way to reduce noise from the background only. I am using CS6, and have Topaz Denoise 5. I am still learning photoshop, and i assume that i would have to select the subject, what is the best way to do this. I have studied various tutorials on the selection of subjects, but unsure of how to denoise the background only, and sharpen the image only.

I use a Canon 7D, and I find that any higher than ISO 800, puts noise onto the image.

Thanks for any advice :S3:

[Steve Kaluski]

William you can do it within CS6 in ACR without going to a third party very easily, however you can also do it in Canon's DPP too, although someone like Arash is best equipped to help you on that as he knows DPP inside out.

If you want to talk tonight let me know, as I don't have time at present to type out the steps.

Steve

[Diane Miller]

NR is such a subtle change, most of the time (in PS) I can select the subject with the Quick Selection tool, feather it a little, inverse it and then do NR on the selected area. Zoom in at 100% to make sure the edges are OK. Or better, make a separate layer, do NR on it and use the selection to mask out the subject you don't want to mess with. Then you can tweak the mask edges as needed with a fine brush.

You don't want to do NR so heavily that the edges show -- like sharpening, it isn't exactly a perfect solution. Subtle improvement is the best goal.

Anything you do in the RAW converter is glued into the image -- I prefer to do anything above the default NR later in PS, with more control.

[Dennis Zaebst]

William,

Just some additional thoughts:

Others have had good success using Topaz Remask. I have it and use it on some images to select either the subject (which is to be sharpened) or the background, which is to be denoised or blurred.

I have had good success with using the adjustment brush within LR 5.3. It allows you to make a variety of local adjustments with little effort or pain. ACR within CS6 has the same tools, but here's the difference: CS6/ACR changes are applied to the original image, while those in LR are not. It's easy to undo literally anything you do within LR. I also find tools like the adjustment brush easier to use in LR; for example, you can change the size of the brush while you are working by simply rolling the wheel on your mouse (true in Windows version but MAC mice might not have the wheel).

[Dennis Zaebst]

Here's an example of a photo in which I actually blurred the background. The original background was quite busy, I assure you. If you are only denoising however, it is much easier to make a selection, since the boundary between subject and background doesn't need to be as precise.

[Steve Kaluski]

Hi Dennis, no need for the wheel unless you feel far more comfortable, just use the square brackets on the keyboard. :S3:

[Dennis Zaebst]

Ah yes, thanks Steve. I'm always learning stuff here:tinysmile_shy_t:. With the wheel, I don't have to take my hand off the mouse or look down and find the bracket keys though. :t3 I guess it's all just what you're used to in the end.

[Steve Kaluski]

Indeed it is Dennis. :w3

[Diane Miller]

I have had good success with using the adjustment brush within LR 5.3. It allows you to make a variety of local adjustments with little effort or pain. ACR within CS6 has the same tools, but here's the difference: CS6/ACR changes are applied to the original image, while those in LR are not. It's easy to undo literally anything you do within LR.


That's not the case about that difference in LR and ACR. LR keeps a history panel that stays with the image as part of the catalog. When you see the RAW file in the filmstrip you see the history of your adjustments along with it and you can go back to undo it. But if you go back to an adjusted RAW file in ACR, the adjustment slider positions are still there, but you have to remember you did one of the less-obvious adjustment brush things, like a gradient. Then you can click its icon and go back and see the sliders and change them. It's just that you need to remember you did it -- or click the various icons to see if it shows a dot on the image to indicate there was one of the adjustments. Definitely can be edited, just a little harder to find. But there is usually so much stuff in the History it's not so easy to find these less-obvious things there, either.

LR is WAY more sophisticated than Bridge for browsing your files.

[Dennis Zaebst]

Well, that's why I make posts here, so I can be properly corrected:tinysmile_shy_t:. But you are right that that undo feature is hard to find in ACR...so hard to find that I didn't know it was there:t3. Oh well.

So, keep Exposing To the Left. Isn't that what ETL means? (Somehow, I can sense another correction in the wind).:c3:

[Diane Miller]

Sorry -- I didn't mean to be brusque -- always too busy for my own good (or yours).

It isn't really the sort of thing we think of as an undo feature. And it is certainly glued into the PSD file. That's one of the nicest things about LR, which you rightly praise -- all the adjusted RAW files are right there, alongside any derivative PSD files (if people choose to manage them that way). There are a lot of files that I don't need to take into PS these days.


ETTL - I think that's something about flash... (Which can help you ETTR...) :w3

[WIlliam Maroldo]

Adjusting in ACR creates a sidecar file that has the same name as the file with an .xmp extension. All changes to the RAW file are in the .xmp file, and simply deleting it lets you start over. regards~Bill

[Diane Miller]

Or just go to the icon on the right end of the bar that says Basic, for a dropdown list, and choose Camera Raw Defaults to reset everything.