Why do we need expand2sqaure in scorers?

[Hoi2022]

Hello, thanks for your great works.

However, I find that the preprocess inside this looks weird.

The input image is first expanded to a square one, with extra mean-color margins by applying the expand2sqaure function.

I visualized a preprocessed image, which looks like this:

while the original image is:

My teammate also reports that larger aspect ratio results in lower aesthetic score. So we are wondering if this preprocess is correct.

[CarlCloudWang]

In my survey, I found that no expandsqure can promote the capicity of whole model...
u can only use preprocessing from CLIP_ImageProcessor, and this one can cause real improvement.