For measuring the denoising performance of synthetic data examples, where one knows the clean data, I use the signal-to-noise ratio (SNR) (Huang et al., 2016a; Liu et al., 2009a) measurement and the formula is expressed as follows:
In addition to the commonly used SNR measurement, one can also use local similarity (Fomel, 2007; Chen and Fomel, 2015b) as a convenient tool to evaluate denoising performance. The abnormal area in the local similarity map with high similarity indicates the area that contains significant signal leakage in the removed noise. A local similarity map with values that are close to zero, as well as the observed significant amount of removed noise, provides a valid support of a successful denoising performance. In addition, the local similarity measurement can be used in many cases since the input data of local similarity calculation are just the denoised data and removed noise. It provides an alternative in the case of field data processing, where the clean data is unknown and the SNR based evaluation becomes unavailable. Besides, local similarity is a local measurement of denoising performance, whereas the SNR is a global measurement, which cannot guide us to pick out the areas with poor denoising performances.