Join Tim Grey for an in-depth discussion in this video Applying noise reduction, part of Lightroom 4 Image Optimization Workshop.
In many cases, noise can be a challenge in digital photography. Noise is the random variation of tonal or color values at the pixel level. And it's most prevelant in situations where we're using a high ISO setting which increases the amplification of the signal on the image sensor for the camera. Or under low lighting conditions with long exposures. There are a variety of things that can effect noise. But generally speaking, we'll want to minimize that noise as much as possible. I'm going to go ahead and zoom in on this image. I'll zoom to a 4 to 1 zoom setting. And we can see there's a fair amount of color noise in the image, some random color variations.
And also some luminance noise, variations in the overall tonal values that should not be there. On the right panel in the Develop module, I can scroll down to the details section. This is where we are able to apply sharpening to the image, but we can also apply noise reduction to the image at the same time. Noise is exhibited either as illuminance variations, brightness variations between pixels, or color variations. Generally speaking, I would say that the color variations are more offensive. But of course, luminance noise can be a problem as well. Let's start off with the color noise since that's most obvious in this photo.
The controls here are actually quite simple. I can increase the Color Value, which is the Color Noise Reduction Value. And you will see quite clearly that color noise is being reduced rather significantly. Now, as we increase the Color Noise Reduction, we're actually averaging out color values. So, if we increase this value too much, we will actually see a reduction in the overall saturation in the photo which can be a bit problematic. So generally, we want to use the minimum value that produces a good effect within the image.
We'll often not be able to eliminate noise all together so it's more a matter of reducing it to an acceptable level. Once we've adjusted the Color Noise Reduction value, we can also adjust the Detail slider, and this determines how much detail enhancement will be applied. If I enhance too much detail, you can see that some of that noise starts to come back into the image. And if I reduce it too much, then we start to see a softening and a reduction in saturation for the image. So, we'll want to fine tune the balance for that Detail slider in order to produce the best result.
Next, we can turn our attention to luminance noise. Once again, those are variations in tonal values. And we can see some of that within the image here. If I increase the Luminance slider, you'll see that that noise starts to disappear, but you'll also see that detail starts to disappear. We start to see something of an out of focus effect in the image, which can be very problematic. And so, with the Luminance slider, it's even more important to make sure that we're using the minimum value that will actually produce a good result. We don't want to raise it too much.
So in this particular photo, I think, right about there will probably work out pretty well. We reduced the appearance of noise, but not softened the image too much. I can then fine tune the degree of detail that I want to preserve within the image moving to the left we'll see more of the softening effect. Moving to the right, we'll start to see a little bit more detail present within the photo. And we can also adjust contrast, obviously as we average out luminance value within the image. We can start to see a loss of contrast and so fine tuning that Contrast slider can help improve the effect to final result in the image. Obviously, whenever possible, it's best to avoid noise in the first place. Capture the lowest ISO setting possible try to avoid long exposures or getting your camera too hot.
But in situations where you simply can't avoid the noise, you can reduce the effect of that noise with these noise reduction controls in the Detail section of the right panel. Just keep in mind that you want to use the minimum amount for both luminance and color noise reduction production to achieve a good result, so that you're not adding new problems to your photos.
- Evaluating images
- Seeing a before and after view
- Correcting mistakes with the History and Snapshot features
- Develop module basics
- Fine-tuning with the Tone Curve
- Sharpening an image
- Painting adjustments into an image
- Image cleanup
- Creative adjustments
- Duplicating adjustments