“…The former methods are used to assess the quality of the generated results by using subjective evaluation, and the latter methods are used to evaluate model fitting in the echo domain and image domain by using the following evaluation metrics. - NCC: The similarity of the two signals is assessed with the NCC [29]. When it is −1, the inversion signal is negatively correlated with the original echo, when it is 0, it is not correlated, and when it is 1, it is positively correlated.where M and N represent the number of SAR signal data range lines and range sampling points, respectively, a and r represent the azimuth and range positions, respectively, J ( a , r ) represents the jamming signal, E ( a , r ) represents the original echo signal, μ J and σ J represent the mean and standard deviation of the jamming signal, respectively, and μ E and σ E represent the mean and standard deviation of the original echo signal, respectively.
- PSNR: The PSNR [30] is a quantitative metric to evaluate the quality of the inversion image according to the error between the original image and the inversion image. It is defined as follows:where MAX represents the maximum value in the dynamic range of the pixel values, and I J and I E represent the inversion image and the original image, respectively.
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