Noise Reduction on Background

[Roger Williams]

Fairly frequently, commentors suggest running NR on the background of an image. I would appreciate some advice on how to accomplish this. I have Neat Image software.

Thanks for the help.

[Ákos Lumnitzer]

HI Roger
I assume you have photoshop?

I usually duplicate the background layer in photoshop then use a Quick Mask to cover the bird and any elements I don't want affected by NR, then run the Neat Image application from photoshop's filters menu that should take care of all unmasked areas for noise.
You can probably do the masking in NI separately from photoshop, but I haven't worked that out yet.



1- You need to see the layers palette by pressing F7 (palette should show in LRC of monitor)
2- Right click the background layer image and select duplicate layer from the menu, press ok
3- Make sure the duplicated layer you just created is highlighted in blue inside the layers palette (this ensures the original layer remains untouched)
4- Press Q to enter quick mask mode
5- Press B to select the brush tool and make sure you have a standard circular brush
6- use the brackets [ and ] to change the size of brush
7- ensure the color of the brush is set to black in the tool palette and the other color is white
8- paint over the area you want COVERED up - don't panic, the brush will paint in red, which is the QM default color
9- if you accidentally cover an area you don't want to, press x to change the color from black to white and paint over the area you want uncovered
10- when you covered (masked) all areas you DO NOT WANT TO REDUCE THE NOISE OVER press Q to exit the quick mask mode
11- you'll see a marching ant selection around the masked area(s) - you can paint over many areas and the areas do not have to be connected, if you know what I mean
12- go to filters>neat image and apply the NR to taste
13- you are done

I hope this was helpful. There are many ways, sometimes much easier. For example, if you have a VERY clean BG and well defined subject, you can use the magic wand (M) to select the subject, but then you need to invert the selection (SHIFT+CTRL+I) otherwise the bird will be selected and NR will be over the bird NOT the BG.

[Simon Bennett]

Roger, I use Neat Image on virtually all of my images and almost always apply it to the whole image. If the subject is well exposed and not cropped too much I very rarely find there is loss of detail to the subject. Generally the only time detail is lost with dark colors like brown-reds and with heavily cropped images. In those cases I will selectively apply NR. Simon

[Gerald Kelberg]

Hi Akos,
Thanks for the summary.
One thing that I ponder over is the accuracy of the selection. With a soft brush, even with the greatest of care, you are going to be all over the edges - like a kid colouring in with crayons! How far into the background should the selection extend? Should it be solid red on the bird with only the softer colour extending into the background?

Regards,

Gerald

[Del Cockroft]

Hello Akos,
Very good tip, appreciate it.
Regards
Del

[Charles Glatzer]

I have for years now used an Edge Mask for Sharpening, and a Surface Mask (the inverse) for noise reduction on areas only lacking detail. Thereafter, you can apply the Sharpening/Noise Reduction effect to the image layer, tweak/modify the mask(s) any way you desire, vary layer opacity, etc. Additionally, using Smart Filters allows further modification in the post-processing workflow when resizing your working file.

http://www.thelightsrightstudio.com/...askToolkit.htm

For the record, when using an Edge mask I rarely need to apply noise reduction.

Best,

Chas

FYI-the entire process above and more are covered in our Advanced CS4 and LR2 workshops.

[Ákos Lumnitzer]

Gerald
I try to be careful around the edges and even zoom right in, and use a hard edge brush. If I accidentally paint over an area that I do not want to mask, I change the brush color to white and paint over the areas that I want to erase. Then revert to black and keep masking.

You are welcome Del. Just think about this: About four months ago I never even knew what a QM was! :)

Thanks Charles for those tips. :)

[John Chardine]

For a simple, quick, and easy approach in Ps, use the Blur tool with a soft-edged brush of the appropriate size to "run-over" the noisy areas in the BG or wherever you want to direct some NR. You can change the Strength of the tool and the blending mode.

[Charles Glatzer]

For a simple, quick, and easy approach in Ps, use the Blur tool with a soft-edged brush of the appropriate size to "run-over" the noisy areas in the BG or wherever you want to direct some NR. You can change the Strength of the tool and the blending mode.

John,

Try using the Blur tool with darken and lighten blending modes for greater finesse.
FYI- darken mode works great for knocking down specular highlights, etc ;)

Chas

[Kaustubh Deshpande]

Mine is a simple method without use of layers. I use the quick selection tool to select the background. Fine tune using the 'refine edge' to make sure the bird's (or any other subject for that matter) edge is not selected. Then I do NR using the basic photoshop elements 'reduce noise' function. I do this after resizing. takes 2-3 minutes max.

KD

[Kiran Khanzode]

I might be in the minority here, but I hardly ever use Neat Image. I overexpose a bit to the right, noise is not a big issue for me. I just do some guassian blur on the grainy parts...just like what John says above. Will try the lighten/darken blend modes..as per Chas.

[Roger Williams]

Thanks for all the comments and suggestions. I'll have to practice reducing background noise with your various ideas.