The Noise Reduction layer reduces the noise present in photographs that have been taken in low light situations.
This slider controls the amount of noise to remove from the image. Higher values will be more aggressive at removing the noise from the image, though finer details could be lost.
This slider controls how much detail to preserve in the image. Higher values will remove more detail and help remove more noise. Lower values will preserve more detail, but will also leave more noise in the image.
Note: Noise reduction is a time consuming process, and this effect can take a long time to complete. Larger images and older computers will make the process take even longer. Also, moving the Amount slider to higher values will increase the amount of time needed to finish the noise reduction.