Tuesday, December 21, 2010

Lightroom Noise Reduction

Last week we began reviewing the Detail Panel in Adobe Lightroom 3 by discussing the Sharpening controls.  We continue our discussion of the Detail Panel this week with a look at the Noise Reduction options.

Generally speaking, photo "noise" falls into one of two categories which Adobe refers to as "Color" noise or "Luminance" noise.  Color noise appears as those pesky red, green or blue spots in your image whereas Luminance refers to the grain introduced in high ISO or high contrast images.  You may have noticed that Adobe titled this section of the Detail Panel "Noise Reduction" and not "Noise Elimination".  As you'll soon find out, tackling image noise is a game of give and take when trying to keep areas of your image sharp at the same time.

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The above image of the osprey against the bright blue sky suffers from luminance noise which appears as grain or speckles in the blue sky (click for larger image for better viewing).  You'll notice that Lightroom automatically applied some Color noise reduction on this image simply because it's in a RAW format.  As there are no visible red/green/blue noise areas in the image, we'll leave that as it stands.

Much like the Sharpening controls, the Noise Reduction controls are best used when zoomed in at least 1:1 on the image.  In the above screen capture, the image is shown at 1:1 while the preview window on the sidebar is set to 2:1.

To begin reducing the noise, simply click and drag the Luminance slider to the right.  To illustrate the need for "balance", I've pushed the slider all the way to the right on the image below.

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You might think that if a little noise reduction is good, than a lot of noise reduction is better?  Well, as you can see from the above image, we've completely removed the grain or speckles from the blue sky.  Unfortunately, we've also turned the osprey into a "plastic fantastic" by smoothing over any feather detail.  Noise reduction does NOT discriminate between the various areas within your image.

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In this third image, you can see I was much more conservative with the Luminance slider.  I've pushed it far enough to the right to reduce much of the visible noise in the sky area but not so far as to sacrifice too much of the feather detail.  I've also pushed the Detail slider a little further to the right to help pull back in a little more sharpness... which also introduces more grain...and around and around we go :).  The contrast slider does exactly what you would assume in that it helps to preserve the contrast in your image.

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The final image above shows a before (left) and after (right) comparison zoomed in at 2:1 (click for larger image).  As you can see the noise in the blue sky is visibly reduced and we've retained most of the feather detail on the osprey.

The Noise Reduction options within Adobe Lightroom 3 are really pretty amazing and can help you to salvage noisy images without ever having to leave the comfort of Lightroom.  As we've seen, however, there is no magic bullet.  It's a game of give and take between smoothing out the noise while retaining sufficient detail which can only be accomplished through some trial and error. 

That's all for this week's tip.  Until next time, keep on click'n.


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