Carousel Blog images poor resolution

[ Moderator note: moved to Fixing WordPress. ]

Hey guys,
I’m having great difficulty in finding the perfect image size for my carousel in my blog. I’m using a file size 476×714 @72dpi with an overall file size of 300KB.
Once i upload to the carousel, the resolution is far from being usable. Lots of “blurriness”. I understand there’s a fine line between having a great displayed image, and the overall download time of the images, but i’m struggling to even find that fine line.
The URL is https://dev.crcooperphoto.com/curabitur-rutrum-ante-vitae-nisi-mollis-quis/
(don’t pay attention to the words, automated draft)
As you can see, the images are not usable. There is 4 different sized images(but the same KB size as mine) in amongst them(saved from the web, not my photos) and even they look ok, in comparison.
If you right click my image and open it in a new window, the resolution is definitely acceptable.
The only thing i can think of is that there might be something in the carousel program that is only displaying a certain resolution. Almost like a thumb nail, to eliminate long download times?
PLEASE HELP!