General
Google has come up with an algorithm that reduces JPGs by 35%, or maintains existing file sizes but dramatically improves quality. The new JPG is 100% compatible with existing programs and web browsers on all platforms. It’s 100% open-source and compatible with the current JPG standard.
And not a single person will ever use it.
Read more “Google JPG is 35% smaller/higher-quality – but you’ll never use it”
Adobe InDesign

When exporting as JPG from Adobe InDesign, most users export an entire page, then do any cropping necessary in Photoshop. But there’s an easily missed feature that allows you to export only what you want.
Simply select the object(s) on your InDesign page that you want to export before hitting Command + E (File>Export) and choosing JPG from the drop-down menu. When the JPG Export dialog box appears, tick the Selection button at the top before setting your other JPG options. InDesign will export a flattened JPG the size of your object(s) at your specified resolution and color mode.