File not found on Windows devices

When I run the inference script with windows paths I get FileNotFoundError.

Input:
```python inference.py --img_path input\IMG_0416_640x480.png --restore_from=pretrained_models\ResNet101```

Error:
```FileNotFoundError: [Errno 2] No such file or directory: './output/input\\IMG_0416_640x480.png'```