Maybe that is the photographer in me speaking, but when I hear the word 'portrait' I immediately think of an image of a person (and similarly for 'landscape', I think of an actual landscape) and I only interpret it to mean the orientation of a non-square rectangle if it is used together with the word 'orientation' (or similar).
Note that the 'Portrait' mode also automatically switches you to the longer focal length thus already indicating to the user that this is for a tighter shot which is associated with people shots. And people aren't stupid, they know very well that can turn the phone to switch between portrait and landscape orientation in the default 'Photo' mode (but also in the Time-Lapse, Slo-Mo and Video mode). And once they tried the 'Portrait' mode a couple of times, they'll know that it results in a blur of the background. And in many languages, 'portrait orientation' actually is described using a word that is not a synonym for 'picture of a person', among them Spanish (formato alto vs retrato), Italian (formato verticale vs ritratto), German (Hochformat vs Porträt), Polish (format poziomy vs portret), Russian (вертика́льный форма́т vs портре́т).
[doublepost=1474549731][/doublepost]
There are some limitations on the length of such a label.