Image Quality Poor On Items For Sale

I am using the Highend Theme. This is a new WordPress install. I have a couple items added to the “Products” page. The Thumb nail is very poor quality on the Home page even though I am using high quality images. I sized the images 271 x 271 then 800 x 800 then I tried 1200 x 1200. When I click on the image to view it on the Buy Now page the images are great. Can someone help me figure out what I am doing wrong so I can correct this problem?

I ATTACHED A SCREENSHOT OF MY PRODUCT SETTING PAGE
If you need login tell me how to send info private.
http://www.jpsministries.org
I have it on “Coming Soon”