As photographers, we often work in light situations that are... less than ideal. One common way to deal with low light is to cranking up the gain, also called the ISO, on your camera. Unfortunately, the outcome is blotchy, splotchy areas that might distract from an otherwise perfect photo.
Luckily, it's easy to reduce and remove that noise with the help of Adobe Lightroom. In this tutorial, you'll learn how to do just that.
What is Noise?
Digital noise is the grainy, dotted texture that you've likely seen in photos. It's most noticeable in the darkest areas of photos, like the shadows in nighttime photography.
As you increase the ISO (sensitivity) setting, you're asking your camera to interpret more information from the signal (light) that it's getting. This creates noise in high-ISO situations.
Noise has always been a part of photography. High-ISO films were always more grainy and stippled than the low-ISO alternatives. However, noise in digital photography is generally less visually appealing than the "organic" grain look of film.
Here are three everyday situations that create noise:
- You shot an image at a high ISO setting, particularly on older cameras or a camera with a small sensor, like a smartphone
- You underexposed a photo while capturing it, and are now drastically increasing the exposure while post-processing
- You used a very long exposure that caused the sensor to heat, which creates noise
Digital noise is distracting. Camera sensors keep improving, but noise is still unavoidable, particularly at high-ISO settings. Let's learn how to reduce it while post-processing an image in Adobe Lightroom.
Settings That Increase Noise
You might notice as you increase specific sliders that your noise increases too. Most of these live on the Detail panel.
Any slider that increases detail is sure to enhance the presence of noise. Here are a few sliders to work with carefully in already noisy photos:
One way to manage this "byproduct noise" is to apply adjustments selectively. Read on for a technique to do just that.
When you're applying noise reduction, it's essential to view your image at a variety of zoom levels. Make sure and zoom in to 100% so that you don't remove too much detail from your subject.
Global (Whole-Image) Noise Reduction in Adobe Lightroom
Start by switching to the Develop module.
This is Lightroom's workspace for making visual adjustments to an
image. In this part of the tutorial we'll deal with noise that's present
in the entire image.
Luminance Noise Reduction
noise is tonal: it's perceived in the shadows and darkest parts of an
image. It's the pixels that have misfired to the wrong tone (of
greyness). Luckily, Lightroom handles this kind of noise well.
- Set zoom to 100%
- Find the Detail panel on the right side and scroll down to find Noise Reduction
- Under Noise Reduction, set Details to 100%
- Set Luminance to 100%
- Slide back Details slider until artifacts disappear
- In area of fine detail, slide back Luminance slider until detail returns
Use the Contrast slider only with extreme noise. It's better to just accept a little noise.
Colour Noise Reduction
kind of noise is pixels that have mis-reacted to the wrong color. It
shows up as blotches, most prominently in shadow areas. Again under Noise Reduction, the Color slider works by desaturating the shadows. Move up only until noise disappears. The Details slider is ineffective, you can leave it alone.
Selective Noise Reduction in Lightroom with the Adjustment Brush
Reducing noise is always a balancing act:
- If you apply Noise Reduction, you lose detail as Lightroom smooths the image
- If you add detail with sliders like Clarity and Sharpness, noise increases in lockstep
The balance is applying detail enhancements that enhance only certain parts of the image. Many times, noise is most apparent in low detail, background areas, so there's no need to increase the detail in those areas further.
The Radial Filter, and the Gradient Filter and the Adjustment Brush have a slider that will allow you to adjust the noise in only the areas where these tools have effect. My preferred solution is to use the Adjustment Brush. It takes more time, but it gives you selective control while applying adjustments.
In Lightroom, make sure you're working in the Develop module. Underneath the histogram is a series of icons. Click on the one on the far right, the Adjustment Brush, then find the slider labeled Noise. Dial this down, then brush over selected areas that are noisy.
I'll use this approach to reduce noise in the background and other
distracting areas. This preserves detail in the subject and focus of the
Remember, specific settings also increase noise as a byproduct. Consider applying those adjustments like Clarity and Sharpness only to specific areas.
OK, But: What is Noise?
The word "noise" is most commonly used to describe a sound, often a loud one, that is unpleasant or causes a disturbance. Noise, however, can describe an unwanted irregular pattern that disturbs any kind of signal.
Noise is the same kind of electronic static you'd see on television, hear on the radio, or pick up on a phone call. In cameras, noise presents itself like granules of sand that increase in size, randomness, and color variation as this static increases. Noise becomes especially apparent as the signal from the sensor is amplified. For the most part, better cameras are able to mitigate this static well and full-frame.
The noise in your images increases as you increase the ISO because you're increasing the signal-to-noise ratio: allowing more irrelevant information in. You're certainly able to capture more information as you boost the signal, but you begin to lose accuracy as you do so, creating noise. Noise also happens when you try to amplify or enhance a low amount of source's signal beyond its natural level. These two instances are exemplified when shooting the same scene at different ISOs or when brightening a dark image.
Your camera's ability to mitigate noise is a balancing act between the sensor size and technology, the camera's processor and software, and user input (file type, settings, etc.). It's important to learn this balancing act well in order to create images with less noise. You'll have a better time in post-production when optimizing your images because you've provided the best possible starting point.
How Noise Reduction Works
Noise reduction is simply cleaning up the signals your device (your camera) has received. By reducing the noise, you're left with more signal: you get a cleaner picture. Applying a noise reduction algorithm removes the different types of interference that clutters up your photo. It interpolates (fills-in) the gaps and errors made by the noise.
Completely eliminating noise from an image isn't possible because no signal is pure as-captured. Noise reduction does not mean noise elimination. Because noise reduction can reduce the quality of your image in other ways when over-used, the trick is finding the least amount of noise reduction that will produce an acceptable image for your purposes.
Also, because digital signals are binary — a series of 1's and 0's — you can't have signal and noise occupying the same exact space. Interpolation tries to smooth that out and make an educated guess as what should occupy that spot. If you apply too much noise reduction, you'll lose the detail and color fidelity you were aiming to preserve. The smoothing effect of interpolation turns into broad-brushed smudging.
Just like your camera, applying noise reduction in post-production is a balancing act between the camera's inherent capabilities, software capabilities, and user input. Understanding this and giving yourself the best possible starting point at each step will give you the ultimate flexibility in reducing noise in your photos.
Caution: Sharpening and Noise Reduction
Older cameras or very high ISO images tend to have a lot of noise and require strong noise reduction to improve the image. However, many times strong noise reduction can cause a significant loss of detail due to the blurring effects of strong noise reduction. To counteract this effect, you can apply Sharpening.
Small amounts of sharpening an image go a long way, but it can reintroduce the noise you just removed without refining its application. A Masking slider in the Sharpening tool can help restore sharpness without undoing your noise reduction work. When set to zero, your settings are applied to the entire image. As you increase the masking, the effect's distribution is decreased until only the edges of high contrast areas have visible sharpening. So, you can restore the perception of sharpness by applying it only to the edges of people and things in your image.
What is great about combining Sharpening Masks with Noise Reduction is that there are instances where can use stronger Noise Reduction settings than usual and still maintain edge sharpness. This is great for skin, walls, skies or other smooth surfaces.
Tip: Noise Reduction Presets for Lightroom
The ultimate goal of learning these different aspects of noise reduction is to create reusable presets in Lightroom for each camera and ISO combination. Presets are a huge time-saver. For example, my Canon EOS 1D Mark IV's noise becomes bothersome to me from ISO 3200 and up, so I created presets for them in order to consistently apply batch-corrections for that ISO.
Additional tweaks to these presets such as Sharpness, Vibrance, or Hue-Saturation-Luminance (HSL) settings can also be integrated according to your camera's characteristics. So, if you notice a particular color goes flat at a certain ISO, you can boost it and save it into the preset.
If you want to be very precise, integrating accurate color profiles using an X-Rite Color Checker or X-Rite Color Checker Passport at different ISO settings is the way to go. To cut down on time, only start the process where the noise becomes bothersome and go up from there. Make your noise reduction, sharpness, etc. adjustments and save it as a preset for each ISO.
Although reducing noise in your image begins at the moment of capture — using the lowest possible ISO and nailing your exposure — it is great to have noise-reduction available in post-production. Your camera can only do so much and Lightroom's Noise Reduction is powerfully refined. Good Noise Reduction technique will give you cleaner images and enable you to display your photos larger both on screen and in print. Utilizing presets for Noise Reduction will save you a lot of time so you can work smarter.
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