Lightroom noise reduction explained

Mats Image processing, Learning Leave a Comment

Since i just posted about sharpening, i’ll write one more about noise reduction. Sharpening and noise reduction go hand in hand and in Lightroom, they’re located on the same tab – the one named “Detail”.

As a rule of thumb, you want to do your noise reduction before you do your sharpening, because if you begin by sharpening, you’ll sharpen your noise and it will look worse.

Noise reduction comes with six sliders, but usually you will only be using two of them: color and luminosity. Go into the develop module of Lightroom and you’ll find the detail tab on the right. Notice a couple of very helpful things. First, the exclamation mark (red arrow) that tells you your image is not zoomed in enough to work with noise reduction and sharpening. Click on it and you get a 100% preview. Second, if you click on the black arrow (yellow arrow), you will get a small detail window. Now the exclamation mark has been replaced by a symbol that you can click on to select which part of the image you want to see in your small details window.

Detail tab

So what is noise and why do we get it? Noise is a graininess and pixel-level discoloration of your images that you get when you push your camera hard in situations with less light. If you raise your ISO to be able to get lower shutter speeds in low light situations, you will get noise. Some camera sensors do this better than others, of course. I’m fortunate enough to have lots of noisy images, because i shoot my daughter’s handball team in badly lit places. I’ll set my ISO to 3200, which is very high, to be able to take pictures at reasonable shutter speeds. Let’s look at what Lightroom can do for a picture like this one:

Noise reduction before full size

Let’s begin with both luminance and color noise sliders set to zero. The color slider defaults to 25, but i pulled it down to zero for our starting point. If we zoom in closely on the nearest girl’s face area, we see very clearly that there’s color noise, which is the pixels with different colors. There’s also a lot of luminance noise, which is the pixels that are in the right color range, but too dark or too bright, which makes the stand out from their surrounding area.

Starting point

Our first step is to pull the color noise slider up to around 33.

33 color noise reduction

Notice what a great job Lightroom has done. The discolored pixels are gone. Now we pull the luminosity slider up to around 40.

Luminosity 40 color 33

After this step, much of the grain has been reduced. Since we started with a terribly noisy image, it will never get perfect, but we’ve come a long way. This far is mostly where i’ll go, because i’ve found that working with the other sliders will usually only make things worse. Adding contrast pulls noise back into the image and pulling the detail sliders up or down pulls back noise too. If you go any higher with the color slider, the image will start to fall apart. Here’s our image with the color slider at 100:100 color noise reduction

If we go higher on the luminosity slider, our subject will start looking like a porcelain doll because the grain has been evened out to something that no longer looks natural.

Noise reduction luminosity 100

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