Sony Xperia Z5 Premium uses 4K only in media, 1080p elsewhere

Sony might have struck gold when it announced the Xperia Z5 Premium, the world's first ever 4K smartphone, which also makes it the world's smallest 4K display, However, that adage about not judging books by covers might very well apply to screen resolutions as well. While the manufacturing feat of fitting a 4K display inside a 5.5 screen space is …