Apply on grayscale image

[pjh1023]

Hi, I've read your paper and code and found it very interesting.
One question, if SAN uses channel-wise feature extraction, is it not effective on grayscale images?
I tried to test it myself, but simply changing the code in option.py didn't work. If this model is also effective on grayscale images, can you tell me how to change the code/settings for training? If not, its fine :)