How to interpret score values?

[Ellyuca]

Hi. Thanks for this interesting work.

I want to use this full reference metric to evaluate the quality of some images for my research.

I managed to run the code and I tried a few images from the PIPAL validation set (i.e the image of the parrot A0019.bmp and the image with a house A0020.bmp and their corresponding distorted versions A0019_10_04.bmp and A0020_10_04.bmp).
I used this model: AHIQ_vit_p8_epoch33.pth.

When I compare A0019_10_04.bmp with A0019.bmp I get as score 0.466813. For A0020_10_04.bmp with A0020.bmp I get 0.589722.
But then when I compare the images with themselves (A0019.bmp with A0019.bmp and A0020.bmp with A0020.bmp) I get the scores 0.691261 and 0.704291, respectively.

I am wondering that is the score range min and max value for this metric? It is 0 and 1?
How do you interpret the score values? Lower means more different? Higher means more similar?
For examples, in the case of other FR metrics like SSIM, when I compare two identical images I get a score of 1, so then I can say that the images are identical. But with your metric, how can I tell if 2 images are the same (or different) just by looking at the score values?

Thank you for your time.
I'm looking forward to your answer.
Have a great day!

[yangyijune]

Same as above.