mobile conversion script for FBCNN (a JPEG artifact denoiser)

mainly for DeJPEG

1. clone FBCNN

2. overwrite models/fbcnn_network.py with my patched one that is ONNX compatible

3. create a Python env

   you know the drill

4. pip install -r requirements.txt

5. download the original FNCNN models and move to model_zoo

6. then edit convert_mobile.py to the correct filenames and run