Labeling images with Imagemagick

I sometimes need to place simple text on images. In one example, I created several versions of the same image with each having a different size. Then I use a HTML <picture> construct to serve up the "correct" image for a given screen size. here's an example:

<picture>
	<source srcset="wullenweber-800.webp" media="(min-width: 800px)" type="image/webp">
	<source srcset="wullenweber-600.webp" media="(min-width: 600px)" type="image/webp">
	<source srcset="wullenweber-400.webp" media="(min-width: 400px)" type="image/webp">
	<source srcset="wullenweber-200.webp" media="(min-width: 200px)" type="image/webp">
	<img src="wullenweber-200.webp" alt="Wullenweber Antenna">
</picture> 

I wanted to label the images with their horizontal size in the lower lefthand corner. Here's the Imagemagick command to place 12 point white text in the lower-lefthand corner of the image:

convert -gravity southwest -pointsize 12 -fill white -draw 'text 0,0 "800"' image.webp image.webp