Noise Reduction for Photographers
Have you ever looked at a photo and noticed a breakup in colours and some odd tones in your shadows? It’s probably down to digital noise. If you want to know about noise reduction, then we’ve got the beginner’s guide right here.
What is Noise in Photography?
ISO is the cause of all matters relating to digital noise and controlling it. The higher the ISO level goes; the more noise will be generated by your camera.
Increasing the ISO makes your sensor more sensitive to light and has the side-effect of creating random bits of data during the light capture which makes the noise.
Noise can reduce the overall quality of your image. It can skew the colours of some pixels making black pixels look grey or flat. This removes contrast and smooth tones and makes a photo look ‘blocky’ and just a general eyesore.
When Can Noise Occur in a Photo?
There are a few situations where noise is more susceptible than others. Long exposures are one of the most common causes of noise in digital photography.
During long exposure shots the sensor temperature rises and the amount of noise increases, especially the chromatic (colour) noise.
The same goes for night-time photos. When you are having to increase the ISO speed to improve your exposure then it’s more likely that noise will appear. It’s only advised to increase your ISO in situations where it’s absolutely necessary.
It’s best to open your aperture wide, improve the lighting (if possible) and slow down the shutter speed (slightly, and remember to use a tripod if shooting below 1/125th) before increasing the ISO.
Entry-level cameras will handle higher ISO levels worse than more premium bodies. Do a few tests at night time to see what ISO level your camera can handle before showing up noise.
How to Stop Noise in your Photos
Here are some practical steps to take to control the noise creeping into your shot in the first place.
- Full frame cameras can handle higher ISO speeds than cropped sensors.
- Shoot in RAW format.
- Set the ISO level to 100 as default and raise it gradually when improving the exposure.
- Expose your images correctly. Be guided by your histogram.
- Long exposures are problem hot spots for digital noise.
- Use lenses with fast (large) aperture settings – F/3.5 and wider
- Avoid using burst mode a lot as this can increase the temperature of the sensor.
Check your camera for a function called High ISO Noise Reduction or Long Exposure Noise Reduction. Turn it on if you know you’re going to need a slow shutter speed or higher ISO setting.
After you’ve taken the shot, the camera will analyse the image and look for any pixels that are incorrectly rendered and do its best to re-correct them. Don’t fully rely on it though as it’s not always perfect.
How to Reduce Noise in Camera RAW
If you have Camera RAW through Photoshop or Lightroom then it’s a good idea to zoom your image to 100% to see the actual details of the noise in the image. Using similar options in both pieces of software we’ll outline a few steps that you can use to reduce those noise levels in your photos.
Lightroom has dedicated noise reduction tools under the ‘Develop’ module and in Camera RAW (for Photoshop users) you’ll find it in the ‘Detail’ tab.
Tips for Noise Reduction in Lightroom
- Luminance Detail – This is good for shots with lots of noise. Moving the slider to the right preserves detail, but can produce noisier results. Whereas sliding to the left reduces detail but gives cleaner results in terms of noise.
- Luminance Contrast – Pushing the Luminance Contrast slider to the left can give smoother results but can also have less contrast.
Image: Noise Reduction Tool in Camera RAW
Image: Noise Reduction Tool in Lightroom CC
The Luminance slider is your main tool in stopping luminance noise featuring in an image but use it sparingly. Editing can only help after the problem has occurred, so it’s better to solve the problem in-camera first.
Secondly, it’s worth using the Black and Dehaze sliders too. They aren’t going to work on every photo, but given that noise occurs, mostly, in darker areas then it’s a good slider to tweak on full view. The Dehaze tool helps by making noise in the darker tones of an image less noticeable.
Hopefully, this guide on how to noise reduction has been insightful for your learning. Remember that shooting at night, indoors in low light and with long exposure photography are the main 3 occasions you’ll need to watch out for noise occurring.
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