Noise reduction

The noise reduction is controlled by NRSigma (denoted by sigma in formula (10) in NAFE paper) which is set in NAFE.ini file. The higher is the value of NRSigma the lower is the amount of noise in low contrast areas of the image. It is not correct to suppress the noise too much because the low contrast details would be lost. The noise must be clearly visible but its intensity must not mask the visibility of fine details. The default value is NRSigma=15.

SDO AIA 171 Å image (NAFE weight 0.2) with NRSigma 10, 20, 30, 40, 50 (from the left to the right).