What do you mean with "srcset"? Save image with several sizes?

And then?

Who or what will where create the needed HTML?

 <picture>
  <source media="(min-width: 650px)" srcset="img_pink_flowers.jpg">
  <source media="(min-width: 465px)" srcset="img_white_flower.jpg">
  <img src="img_orange_flowers.jpg" alt="Flowers" style="width:auto;">
</picture> 

The user? Or automatically?

And that is a very simple example that won't match for 50% of all sites because any template reacts different concerning responsive behavior and available space for the images.

What will happen with all of these images if you change the template and the sizes don't match there. Upload all images again after you've changed the configuration?

How complex would such a configuration become for users?

How complex would a code become that has to check if the images exist before the HTML is inserted in the page?

Or display pixalated images?

Please think before you post feature requests!

I prefer plugins that do these jobs before the then cached images are USED in frontend. Not destructively on upload.

BTW: You got already many answers concerning "resize image on upload" but ignored any aspect of it. "The slaves are on holidays at the moment."

@ReLater secret is a standard for loading images https://css-tricks.com/responsive-images-youre-just-changing-resolutions-use-srcset/

https://extensions.joomla.org/extensions/extension/photos-a-images/images/imgen/
https://extensions.joomla.org/extension/imagerecycle-image-optimizer/

Both are free

Thanks @C-Lodder, closing for the Reason stated in above Comment.

@franz-wohlkoenig "Slow down... you move too fast"

Neither of those extensions are for srcset (unless I missed it) and that really is something that should be possible in core

Thanks Brian for reopening this, cous it realy should be possible in core

is this implemented in J4 ?

No - that's why its an open issue

what needs to be done to include this in J4.0?

@chnnst

what needs to be done to include this in J4.0?

1. A Developer writing an Pull Request
2. Two successfully Test
3. accepting the PR by the Release Lead

Same Procedere on every Issue.

Please test PR #34803