Why does the -o flag create 5 images in different sizes

[ayroblu]

Hi, I was looking at potentially using this but I was a bit confused and didn't find anything obvious that explains why when you try to visualise the difference with the -o flag, it produces 5 images, each of which is smaller than the previous? I assume it's a quality thing, but I probably only want one image? But I don't know, do you mind explaining / adding to the docs?

I'm using Version 3.2.4 on macOS.

[kornelski]

The comparison is done 5 times at different image sizes, to compare details of different scales.

High resolution outputs indicate differences in high frequencies and noise.

Low resolution outputs are differences in big elements and background colors.