Noise reduction in Lightroom has helped me so many times when I’ve had to photograph a wedding in a dark church, or when photographing past sunset. So, noise reduction is great, but what’s even better is avoiding image noise in the first place. Or, at least reducing the possibility of image noise as much as possible before taking the shot.
To understand how to avoid noise in images and then how to reduce noise in Lightroom Classic (or similar), you must first understand:
- What is image noise?
- What causes digital image noise?
Let’s take a closer look…
What is image noise?
If you’re new to photography, the concept of noise in images might still sound odd. How can a photograph be noisy?
In digital photography noise is the equivalent of grain in film photography. It’s the speckling of pixels that makes a photo look a little rough, not so smooth and clear. It’s especially obvious in the darker parts of an image and the out of focus areas.
When you zoom in closely on the computer, digital image noise becomes much more obvious.
This is a very zoomed in section from the silhouette photo on top. I increased the brightness in Lightroom, which made image noise visible.
What causes digital image noise?
The truth is that you can’t be entirely free of noise in photos, even if you think you’ve avoided it. So, to avoid getting overly technical and picky about noise in images, the level of noise that I’m talking about is where it becomes obvious in a photo and starts to ruin the quality of the image. Of course, the more experienced your eye becomes, the more obvious noise will be. But let’s keep this simple.
If you’ve come across any discussion on image noise, you’ve no doubt heard that noise in images is caused by using a high ISO.
Well, that’s not entirely true.
Noise will be far more obvious in an underexposed image with a low ISO than a correctly exposed image with a high ISO. When you try to recover the lost data in an underexposed image using, for example, Lightroom by increasing the brightness of the image, the noise will become obvious.
The reason for this goes back to the fact that there will always be noise in images. The way to fight this is with light. The more light you have in an image the less you’ll be able to see any noise.
Another way that noise becomes more obvious in an image is with long exposures.
How to avoid noise in images
It’s not always possible to avoid noise in images, but here’s what you can do to avoid it as much as possible:
- Correct exposure settings
- Signal to noise ratio
- Add light
1. Set exposure to avoid underexposure
Now I’m not saying that you should overexpose all your photos to avoid image noise through accidental underexposure. That would be crazy, because then you’d never be able to photograph high contrast images. I love shadows in my photography, so for me to create images without any shadows would feel very dull.
Further reading: How to use shadows in photos to add atmosphere
What I’m saying is that you need to ensure that your image is correctly exposed with either a:
- Longer shutter speed
- Wider aperture
- Higher ISO
I’d increase the ISO only if I couldn’t lengthen the shutter speed or widen the aperture. That’s because it’s true that lower ISO’s produce better quality images with less visible image noise than higher ISO’s …when the exposure is correct. When the exposure is not correct and you brighten an image in post production, noise becomes a problem.
Taken at 9.09pm after the sun had set. Camera settings: 1/1600, f3.2, ISO 200. Below is a 400% zoom to show the relative lack of noise.
Below I increased the brightness in Lightroom and you can see how instantly there is a lot of image noise.
2. Signal to noise ratio
To be precise, what we’re talking about is the signal to noise ratio, or SNR.
Put simply, the signal is the light recorded by the image sensor that forms an image. In other words, whatever it is that you’re photographing. If you can’t see the signal (image) clearly, because it’s underexposed, there will be a higher level of noise when you increase the brightness of the image in post production. The signal to noise ratio is low.
If you have an image that has both well exposed highlights and deep shadows, the noise in the dark parts, the shadows, won’t be obvious. Especially as you won’t be increasing the brightness of the shadows, because you’ve recorded enough light. There’s a lot more light than noise – the signal to noise ratio is high. For this reason, high contrast images don’t appear noisy when exposed correctly.
Do you see the difference? It all comes down to how well you expose the image in camera:
- Clearly visible signal (well exposed image), high signal to noise ratio, minimal image noise
- Not so clear signal (underexposed image), low signal to noise ration, more image noise
3. Add light to lift shadows
If there’s not enough light available, you need to add light to the image with:
- Or a reflector to bounce light back onto your subject
Taken at 8.43pm using flash as the sun had set. Camera settings: 1/1600, f3.2, ISO200. The below close up is zoomed in at 400% to show virtually no visible noise.
The sun had set so I lit her with off camera flash. As a result, there is no visible noise in the photo – see close up below.
Camera settings: 1/1600, f3.2, ISO 200. Taken at 9pm.
So, now that we’ve covered what noise in images is and how to avoid it, or at least reduce the amount of noise in an image when captured, let’s look at how to go about noise reduction in Lightroom, or whatever software you use. I’m sure the process will be similar with other photo processing software.
Full frame vs crop frame cameras
Your camera’s sensor size will also affect image noise. The bigger the sensor, the more light it can capture and the less image noise there’ll be. For this reason full frame cameras are better than crop frame cameras for photographing in low light situations.
How to reduce noise in Lightroom Classic
Before we get into how noise reduction in Lightroom works, bear in mind that it should be used sparingly.
Sometimes you need to reduce the noise a small amount to improve an image and that’s fine. It’s when you start making big adjustments that problems creep in. This is because noise reduction in Lightroom (and other software) is not a miracle cure. When you use too much noise reduction, it makes the image super smooth and plasticky. You’ll lose sharpness and it will look sort of out of focus.
So it’s really important to try and capture an image correctly, as you intend it to look, in the first place and not assume that you can fix it in post.
Next essential tip for photos with less noise is to shoot in RAW. If you want to reduce image noise in post production, you’re not going to get far with a JPEG. Not enough detail is retained in JPEG images, because they’re processed in camera, so much of the data is stripped away.
Further reading: Shooting RAW vs JPEG image quality pros and cons
Now, moving on to actually doing something about the noise in images. There are two types of image noise you can reduce in post production:
- Luminance noise
- Color noise (also called chromatic noise)
Of the two, luminance noise is the one we adjust most of the time. Lightroom automatically adds a level of color noise reduction on import, but you can also make further adjustments if you wish.
When using the noise reduction sliders in Lightroom it’s best to zoom in to 100% as this is when the image noise will be most obvious. Lightroom actually shows a little warning if you don’t.
Subtle luminance and color noise reduction applied in Lightroom Classic.
Camera settings: 1/1250, f3.2, ISO 500. Taken at 8.25pm in the last rays of sunlight. I had to use a high shutter speed to freeze motion, so had to increase the ISO.
1. Luminance noise reduction in Lightroom Classic
In the Detail Panel there are three sliders for luminance noise reduction:
Above are the noise reduction settings I used in Lightroom Classic. Below is a close up of the photo.
As luminance refers to the brightness of an image, the luminance noise slider adjusts only the brightness of pixels.
The detail slider helps you to keep some of the detail you lose when applying noise reduction. Again, you need to use this sparingly so that you don’t push it too far.
The contrast slider adds back some contrast that would have been removed in noise reduction. This returns some of the sharpness to the image.
Too much noise reduction results in overly smoothed photo that looks plastic.
I pushed both the luminance slider and the color slider to maximum to show you the effect. Below is a close up so that you can see how detail is lost.
2. Color noise (also called chromatic noise) reduction in Lightroom Classic
When a color appears to have a mass of red, blue, green and magenta dots, instead of being solid, what you’re seeing is color noise. The color noise reduction sliders are below the luminance reduction sliders and are almost the same. They are:
Adjusting the color noise slider will help out, but if you push it too far, you lose some of the natural color variation.
Instead of contrast, in color noise reduction, there’s a smoothness slider, which is exactly what it does. Again, be careful you don’t go too far, because noise reduction will already have smoothed the image somewhat.
In the close up on the left there’s no color noise reduction and you can see speckled flecks of green and magenta. On the right the default color noise reduction has been applied.
Local noise adjustment
Use local noise adjustment to reduce noise in certain parts of an image, instead of the global adjustment that’s made with the noise reduction sliders.
When you select an adjustment tool to reduce noise in images, you don’t get a choice to adjust either luminance noise and/or color noise. It will automatically reduce luminance noise only. These tools include:
- Local adjustment brush
- Radial filter
- Graduated filter
How to remove noise in photos
So, now you know that the short answer is that you can’t entirely remove noise from photos, but you can reduce it to the point of not being noticeable. You can:
- Work to avoid noise when you take the photo
- Reduce noise in images, to an extent, in post production
As each photo, or series of photos, is different, you’ll need to assess if noise reduction is necessary and if so, how much, on a photo by photo (or series) basis.
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By Jane Allan
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