Images for your listings are managed and sized / resized to adopt to the marketplace standard image requirements.
Click on the Manage Images button (image below) in order to manage images for your variations.
You'll now arrive at the Variant Images pop-up window.
From this window, you can choose, for which Option name and Option value you'd like to update the image for.
SellerChamp will automatically populate images for the variants by looking up using the title, ASIN, UPC. You can use those automatically populated images or search for more and add your own images by clicking the + Add More button.
After clicking the + Add More button, you'll be brought to the Product Photos window.
Here you can:
Populate Stock Photos
Browse the web
Confirm all the changes and you're good to go!