1. Hover over the Products icon in the sidebar and select Products:
2. Select the product list that contains the images you want to optimize.
a. To optimize all the images in the product list
Click the Export button:
Select the Images tab and then Resize images and make them web or print ready.
Enter a maximum width or height for the optimized images.
Select web ready images, print ready images, or no compression and then Export.
When your file is ready for export click Download.
b. To optimize only some of the images in the product list
Check the individual images that you want to optimize before clicking the Export button and then follow the steps listed above.
For more information: What is the difference between "web-ready" and "print-ready" images?