The current metrics are MSE, MAE,SNR, PSNR, cross correlation etc Low values of MSE,MAE and high values of SNR, PSNR and cross correlation close to 1 indicate good denoising. But if you consider a signal say x(t) which is noisy and another signal y(n) which is very similar to x(t) and no noise is removed, then the values metrics appear to be such that the signal denoising is good. Infact if you consider simple smoothing filters, the lesser the smoothing, the lesser is the noise removed but "better" are the values of metrics. However in this scenario, no to very less noise has been removed. Thus the metrics are in essence not giving us valuable information. Would like to hear your views about this.