Last week I discussed sharpening in Lightroom CC. It seems logical that this week I travel down the “Detail” workflow to the next set of tools controlling noise reduction. Actually, I think that Adobe should have placed noise reduction above sharpening. In my work-flow, I typically sharpen only after I have taken a first pass at reducing noise. The goal is to avoid allowing sharpening to accentuate the underlying image noise. Regardless of the order in the development module, lets first look at why noise forms in digital images and what can be done to reduce it before the image gets to Lightroom.
What is Digital Noise
Noise generally appears as tiny dots of contrasting tone or color across an image area that should show smooth tones. The pixels in a sensor are not perfect and they all emit a degree of noise along with the light signal they detect. Several factors can make this more apparent in the final image.
|Colonial Marquee, Noise removed and sharpened
Bright vs Dark Areas
|Luminance & Color Noise in Shadows
|ISO 1600 Noise, Obama in Keene NH, 2007
Pixel Size and Density
|Stonewall Barn, Canon G11, 10MP Small Sensor
|One Second Exposure, Lower Purgatory Falls
All photography is compromise. If you lower your ISO to reduce noise, you may need to increase the shutter speed which will have the opposite effect. When not constrained by the need to freeze action, I generally lean toward longer exposures, since it may take a shutter speed of a minute or more before heat will build-up to the point of causing significant noise.
Noise Reduction in Lightroom CC
Ok, you have pulled out your full sized sensor camera, lowered your ISO and exposed to the right, now what can Lightroom do to reduce any residual noise?
The Noise Reduction Panel performs separate adjustments on two types of noise, Luminance and color. Let’s start with the easier of the two.
|Color & Luminance Noise
|Color Noise Reduced, Luminance Noise Remains
|Luminance & Color Noise Reduced
|Local Brush to apply Noise Reduction Selectively to the Background (Red Mask)
The other two sliders in the Luminance Panel control the amount of preservation of image detail and contrast and can be adjusted to taste.
|Final Obama Image, Keene State College Rally 2007
This is just a brief review of the sophisticated noise controls in Lightroom CC. A more detailed discussion could not replace what can be learned by simply playing with the sliders. Try them from their lowest to maximum levels, studying their effects at various magnifications. Have fun and remember, this is Lightroom, everything is reversible, you can’t explode your precious image.