Yes I have a strange pattern in the output. The output of the kernel and after trianing the network on L2 between the generated LF image and the original LF image using this kernel seems ok. but when I check the image after applying this kernel it has strange pattern.
It seems like either the network learned how to produce the inverse of the kernel, even if I added random noise before blurring. 
out_srf_4_test.jpg2000×1500 658 KB
 
out_srf_4_testG.jpg2000×1500 167 KB

if you zoom in the image before gaussian kernel you’ll realize these patterns.