Help in GAN

How do I convert my normal trained GAN model that takes noise as input to generate images to create closest fake images to a given image. I am trying to walk through the latent space by optimising z (noise) and similarly of fake image and real image but it's not working.

I tried changing the generator to take image as input and trained the model on that but results are very bad.

PS I am using transgan implementation

deeplearning fake gan gan model generate generator image images noise normal space through