It looks like you got some decent structures, albeit some unwanted noise here and there.
I will briefly explain how we make rough surfaces in usr_surface_roughness.fsp (2.0 MB). If you choose rough surface from attached file, you can open the script that shows steps for creating rough structures. Here, we first introduce seeds with random amplitudes, and then using a Gaussian filter with defined correlation in x- and y-direction and sigma rms, we can modify the smoothness and the amplitude of peaks.
@aalam and I were originally inspired by the code and we were thinking to import the image and then use a Refractive index monitor, the data of which can be used as input seed in the rough surface code. We were hoping that with some post processing we can reduce the noise and the sharpness of device, as in your image the wrinkles are slightly curved. Unfortunately, this is not a trivial problem and will require fine adjustments of filters. We spent some time on it, but looks like we made it worse the more with modified it.
Overall, the image processing and noise cancelling is a big industry and we were unsuccessful on improving the imported image quality further.
Please let me know if you need further clarification about the code, or if you could come up with ways of removing the noises in your structure.