How to use --ref_img_path argument?

[GungraveJ7]

I use the following command,
python clip_generate.py --prompt "blonde hair and purple eyes and very angry"

it seems to work perfectly, but when I change the reference image path
python clip_generate.py --ref_img_path .\input --prompt "blonde hair and purple eyes and very angry"

it comes out as:
Traceback (most recent call last):
File "clip_generate.py", line 125, in
ref_img = clip_preprocess(Image.open(ref_img_path)).unsqueeze(0).to(device)
File "C:\Work\PythonEnv\PytorchTool\lib\site-packages\PIL\Image.py", line 3227, in open
fp = builtins.open(filename, "rb")
PermissionError: [Errno 13] Permission denied: '.\input'

then I add the filename and run again
python clip_generate.py --ref_img_path .\input\target.jpg --prompt "blonde hair and purple eyes and very angry"

it works but does not start from my reference photo.

Please help! sorry for my poor English.