Archetype Motion Theme - Product Page Topper Images

[NoOrdinaryHeart]

Hi all, having a really hard time, I sure hope someone can help me. 

• I am trying to upload images for the top of each product page but can't seem to get them right (in terms of the size)
• Creating images from Placeit,
• Then, uploading to Photo Pea 
• Using the instructions on the developers website (min 1440 px wide - 810px tall; and or, recommended 2880px wide - 1620px tall), I am resizing them;
• However, no matter what I do they still look blurry/stretched and or way too big for the area

Can someone PLEASE help ? I've tried and tried and tried .. :0(