How and where would I make these edits in my theme for let's say the product images? And also am interested in adding that to wherever images would need to be uploaded?
2) I understand the way to go about high-res images is to upload the largest possible image - for example 2048 x 2048 and then Shopify would automatically serve the high-density version? For example I have a product image set to 620px x 620px in the CSS for which I uploaded a 2048 x 2048 image. Can I expect Shopify to serve the 1240 x 1240 image for retina devices if the scale parameter had been successfully been added to the theme and the 620x620 image to standard resolution devices?