View distance in console is different with view distance in game

As is shown in the pictures attached, the view distance in the console is two less than the view distance set in the game. (What I did in inoutput_changing.png in the game is setting the view distance to 17 and then setting back to 16.)

The actual view distance seems to be the number set in the game: reducing it to 2 and then gradually increasing it to 5 makes the viewable chunks gradually spread, but in the console, changing 2 to 3 and then to 4 outputs nothing (changing 4 to 5 outputs 'Changing view distance to 3, from 2').