To further measure the noise reduct

To further measure the noise reduction effect of theproposed method, the peak signal-to-noise ratio (PSNR) isadopted as the metric. We chose Gaussian noise, salt andpepper noise, and mixed noise as interference signals.Gaussian noise refers to a class of noise whose probabilitydensity function follows a Gaussian distribution (ie, anormal distribution). Salt and pepper noise refers to twokinds of noise: salt noise and pepper noise. Salt noise isgenerally white noise, pepper noise is generally blacknoise, the former is high grayscale noise, and the latter islow grayscale noise. Generally, two kinds of noise appearat the same time, and they appear as black and white noiseon the image. Mixed noise is caused by the accumulationof a large number of fluctuation disturbances randomlygenerated in time. Noise whose value cannot be predictedat a given instant. In this way, the denoising results of themethod in this paper under different types of interferencesignals are obtained. As the noise density graduallyincreases, the desired criterion for the peak signal-to-noiseratio is above 25.