Fig. 7.

The multiplication neural network model for the Fourier ptychographic imaging process in Eq. (9). The input of the network is the n^th CTF and the measured data $\sqrt{I_n}$. The object’s Fourier spectrum is modeled as learnable weights of a multiplication layer. We use a λ-layer to define the Fourier-magnitude-projection operation. The output of the network is 0, and thus, the training process of the network minimizes the loss function defined in Eq. (9).