(Moving our mobile tech discussion to Phab to let the Services folks see it and chime in...)
Readers love the new lead banner images in the latest Android release of the Wikipedia app[0] – but currently, if we wanted to port this design change to the mobile or desktop site, images would be cropped randomly and most of the images of people would have their heads chopped off. No bueno.
The Apps team has used native face-detection libraries to avoid the chopped-off-head problem, and Max from the mobile web team found a library[1][2] that we could use to build a generalizable face-detection service for everyone (apps, mobile web, desktop). In the short term, this would unblock the mobile web team from releasing a design update to give our users more parity between our two mobile experiences (apps and mobile web). This would also unlock our ability to evolve the design of desktop lead images, too, replacing the templates that projects like WikiVoyage are using to create banner images (which are static and pretty broken on mobile).[3]
Face-detection would get us 9/10th of the way to a good user experience, but even in the apps there are currently still some edge-case issues with cropping and positioning, so folks from the mobile teams have also discussed a more general image-positioning service. I'm not one to let the perfect be the enemy of the good, though, so if we could just request help from the Services team to conquer the chopped-off-head problem, I'd be very grateful ;)
[0] https://play.google.com/store/apps/details?id=org.wikipedia&hl=en
[1] https://android.googlesource.com/platform/external/neven/+/master
[2] https://github.com/lqs/neven
[3] https://en.wikivoyage.org/wiki/Template:Pagebanner