td47's answer does not appear to work for my LG UP7570AUE. Not only is there no 123/Input button on the official remote, but the alternate ("...") button is not just above the Settings button either. I found a You Tube video where someone showed how to use the "..." button to access the "Capture" feature on an LG TV, but when I try that I don't see that option on any input. The "..." button does give a menu of choices, which vary by which input or app is active, but I haven't found any which have anything like a "Capture" choice. The YT video did say that "Live TV" should allow it, but neither live TV nor any HDMI input showed me that selection.
I had an iPhone app called "LG TV Remote" which allowed screen shots from the TV into the phone's memory, and that function worked on an older LG TV that I had, but the app won't even connect to the newer UP7570AUE. Also, the "official" ThinQ LG app which does work for several functions of the newer TV does not appear to include anything like a screen shot function. I also tried to downloading about 6 other third party apps which do work for some basic TV control functions, but I have yet to find one which includes screen shot capability.
