Figure 1.
Approximate Message Passing (AMP), a variant of iterative soft thresholding, is used in the CS reconstruction. The 2D Fourier transform (in y𒀓z) and Daubechies 4 wavelet transform were used. The soft-thresholding step is data-driven and based on the undersampling factor and signal level in the highest wavelet sub-band. The AMP term (previous iteration’s residual multiplied by AMP weight) enables fast computation. The stopping criterion is met when the normalized difference of the L2-norm of successive residuals is less than 0.1%.