If you have images in your ecommerce store that you don't want on listings on a Marketplace, you can block the image in Omnivore. The process is the same in Omnivore for all Marketplaces.
This example uses Catch.
Step 1:
Go to the Omnivore Dashboard
Step 2:
Find the product with the image you wish to block. Go to 'Products - Marketplace Name - Manage Listings in the left-hand navigation and search for the product.
Click the product title on the left-hand side of the table to go through to the product page where you will see the full data of that product.
If you have a list of the image URLs you can go straight to Step 4.
Step 3:
Right-click on the image at the top that you want to block and click 'Copy Image Address' or 'Copy Image URL' depending on your browser.
Step 4:
Go to 'Settings - Marketplace Name (eg Catch) - General'. In the field 'Exclude these images' paste the URL. You can add multiple URL's here, add each URL on a new line. Click the 'Update Settings' button at the bottom of the page to save.
Note: please ensure there are no spaces on either side of the URL.
Step 5:
Go to the dashboard and click 'Upload to Marketplace Name' and wait for the sync to finish.