Implementation of the discriminator network for the adversarial component of the perceptual loss.
patch_size: integer, determines input size as (patch_size, patch_size, 3).
kernel_size: size of the kernel in the conv blocks.
model: Keras model.
name: name used to identify what discriminator is used during GANs training.
model._name: identifies this network as the discriminator network in the compound model built by the trainer class.
block_param: dictionary, determines the number of filters and the strides for each conv block.
def __init__(patch_size, kernel_size)