WordPress produces:

<img src="summer.jpg" 
     srcset="summer-large.jpg 1024w, summer-medium.jpg 640w, summer-small.jpg 320w" 
     sizes="(min-width: 500px) 50vw, 100vw" 
     alt="Alt text">

Then the Adaptive Images plugin transforms this to:

<img data-adaptive-images-src="summer.jpg" 
     data-adaptive-images-srcset="summer-large.jpg 1024w, summer-medium.jpg 640w, summer-small.jpg 320w" 
     sizes="(min-width: 500px) 50vw, 100vw"
     alt="Alt text">

Which in the browser on DOM load becomes:

<img src="summer.jpg?resolution=360,1"
     srcset="summer-large.jpg?resolution=360,1 1024w, summer-medium.jpg?resolution=360,1 640w, summer-small.jpg?resolution=360,1 320w" 
     sizes="(min-width: 500px) 50vw, 100vw" 
     alt="Alt text">