Images scaling to max width 800 pixels... is this intentional?

I'm just curious - for ride reports and other images, I am linking to images I have in my own web space. I typically pre-format these to 1000 pixels wide, but in some cases leave them 1920. Regardless of how I format them, the site is auto-formatting them down to 800 pixels. This is for width, only. Height formatting appears to work fine.