Image partial for responsive images in Neos – Included in https://speakerdeck.com/aertmann/tasty-recipes-for-every-day-neos

Images.html

{namespace media=TYPO3\Media\ViewHelpers}
<media:image
	additionalAttributes="{srcset: '{media:uri.image(image: image, maximumWidth: 400)} 2x,
		{media:uri.image(image: image, maximumWidth: 200)} 1x'}"
	asset="{image}"
	alt="{alternativeText}"
	title="{title}"
	maximumWidth="200" />

Output.html

<img srcset="/_Resources/Persistent/50c6488589075ac9438ae888305d005532702d10/picture.jpg 2x,
	/_Resources/Persistent/7f9a8873fd4095f814ffaffbb17f49343be9b29d/picture.jpg 1x"
	width="200"
	height="150"
	src="/_Resources/Persistent/7f9a8873fd4095f814ffaffbb17f49343be9b29d/picture.jpg">