Hello,
I tested it out with 4:3 and 16:9 resolutions with image sizes 5312×2988 and 1920×1080. None of them were of good quality ones I added them on slider.
I added the link below to show the difference between my taken image and the one that is added on the slider.
Left one is the original, and the right one is the shown image on the slider.
This was cut out of the whole images because of the backgrounds, but you can still see the difference in quality.
Difference in quality
