'data-src' only

<img data-src="https://demo.sirv.com/Model-X.jpg" class="Sirv">

'data-src' and scaled 'src'

<img src="https://demo.sirv.com/Model-X.jpg?w=200&q=30" data-src="https://demo.sirv.com/Model-X.jpg" class="Sirv">

'src' with original image

<img src="https://demo.sirv.com/Model-X.jpg">

No scaling, alt added manually, lazy loading should be added manually

'src' with scaled image

<img src="https://demo.sirv.com/Model-X.jpg?w=400">

Scale added manually to image URL, alt added manually, lazy loading should be added manually

'srcset' with pixel density

<img srcset=" https://demo.sirv.com/Model-X.jpg?w=400 1x, https://demo.sirv.com/Model-X.jpg?w=800 2x, https://demo.sirv.com/Model-X.jpg?w=1200 3x">

'srcset' with breakpoints

<img srcset=" https://demo.sirv.com/Model-X.jpg?w=400 400w, https://demo.sirv.com/Model-X.jpg?w=800 800w, https://demo.sirv.com/Model-X.jpg?w=1200 1200w, https://demo.sirv.com/Model-X.jpg?w=1600 1600w" sizes="70vmin">