Most of the time when you are in a low light situation, you are shooting at high ISO rates. With high ISO digital noise is introduced. The quantity of noise depends from camera to camera and if you are using full sensor or not. Also, sometimes even if you are shooting at lower ISO rates and your photos comes underexposed and you try to open up the shadows in post-processing software, shadow areas will be filled with obvious grains and in long exposure shots, the sensor gets hot and noise might be introduced as a result.
This being said, it is always better to shoot at the lowest ISO possible because de-noising comes at the expense of loosing details in your photos. This is because the de-noising process smooths out pixels in your photo.
Types of noise
1. Color noise (or "chroma" ): materialized as multicolored pixels in areas of the photo that should have been solid colors.
2. Luminance noise: more of a grayish grain in the shadow areas.
See Fig.1. for types of noise that can materialize in your photos.
Removing noise in Lightroom
Removing noise in Lightroom should be done as a final step in your workflow and this usually before or just after sharpening. This is because when you are doing global and /or local adjustments, you might be introducing some noise (especially if you are lightening the dark areas of the photo). To remove noise from your photo, go to Lightroom's Detail Panel in the Develop module. In the Details panel, you will find two sliders for Luminance noise and for Color noise (Fig.2.)
I have recently knew that for RAW files, Lightroom automatically applies color noise reduction in the import process. So you might notice that the Color Noise Reduction slider will be set, by default, to 25 with Detail and Smoothness set at 50 for RAW files. The Luminance noise slider will be set at 0, with Detail at 50 (see screenshot on the right)
Adjust the sliders for color and/or luminance. If you are unsure what type is the amount needed try taking the sliders to the extreme right and back to the extreme left, then reduce your swing process to find a sweet spot between good reduction of noise and retention of details and clarity. At all times, try to avoid going beyond that sweet spot because you will lose some detail in the photo.
Once you have adjusted the Luminance Noise slider you can then adjust its Detail and Contrast sliders. The Detail slider controls the luminance noise limits – higher Detail value = more detail in the photo but, at the cost of further introduction to noise. s a result. Be subtle with your adjustments at all times.
The Contrast slider controls luminance contrast. High values = more contrast but at the cost of new introduction to noise. Lower values will give you a smoother result but again at the expense of reducing contrast. Always balance Detail and Contrast to a little pinch her and there depending on your ISO speed and photo. See Fig.3.
For Color Noise there are two sliders: Detail and Smoothness (introduced in Lightroom version 5.2). The Detail slider is similar to the Luminance process. The Smoothness slider will reduce artifacts introduced in the process.
There you go! It was easy wasn't it? If you have any inquiry or question / comment, or you just want to share your experience in noise reduction, please share in the below Disqus form.
- Start with Color noise reduction and then move to Luminance
- Zoom in at your photo to see noise clearly
- After processing your photos after a shoot, filter your library to higher ISO metadata, and reduce the noise accordingly. Anything above ISO 800 should be processed for noise reduction.