I'm working on an ecommerce site and I am trying to figure out at which resolution to save product images.
We usually go for 72DPI but I believe now we should be using PPI, but also that to account for retina displays we need to save two versions of the image; if we want the largest zoom size to be e.g. 300x300px, there needs to be a 600x600px version so it's not blurry on retina.
Does that mean we need to host two versions or one big one which is downsized for non-retina, and if so, does that affect the speed of the website?
But what PPI do I save these images at? Or is it 144DPI at 2x?