I will use the CF type "Single Image" because my images are already in the WP library.
As for the Media Settings in WP, I customized the sizes as follows:
- Large: 1280x720
- Medium: 640x360
- Thumbnail: 240x135
So each of my images exists in 4 versions (1 original, 3 smaller generated by WP).
Now, let's say that I really want to optimize my site speed. One of the optimizations is to use image sizes that are proportionate to the user's device.
So here's my point: how to make sure that WP always calls/loads the most relevant size when I use the "Single Image" field type?