You may be as skilled as you like, still, don't let yourself be tempted by the first two pictures, to do the headlamp adjustment yourself. It's simply not worthwhile, the workshop will do a yearly check for nothing, every year in autumn. (see video 1below), and remember, they have the correct equipment.
Indeed, as shown in the pictures above, checking the position of the headlamps in front of the closed garage door, does make sense. As you can see, you can remain seated in the car. For those who really want to make certain, they can draw one horizontal line and another two lines, each at an angle of 15° on the free rear wall.
Headlamp height: 0,65 m, light-beam length: 65 m -> 1%
All you have to do, is determine the height of the headlamps with only one person sitting in the car, and then read off the very important percent-rate on the headlight. If, e.g., it shows 1,2 percent, the height of the line to be drawn, per meter from the car, must shrink by about 1,2 centimetres. The diagonal lines of course, cut this line exactly the same distance apart as the centre of the headlamps are from each other.
Now, you've done more than enough. In the workshop, the testing device substitutes for the garage wall. Through a suitable lens, which faces the headlight, it is not quite as fastidious as far as the exact positioning of the device in front of the headlight is concerned. Of course the tyre pressure must be correct, the workshop floor must be suitable and the testing device must be accordingly set up.
You would probably even succeed in correcting the height of your headlamps. Provided of course, you find the right one of the two screws and the suitable place to insert the screwdriver. Hopefully there is enough room to work in, this is stipulated for newer EU-cars in the event that a light bulb has to be replaced. The judgement of the horizontal adjustment should be left to someone who does this job on a day to day basis.
After all, headlamp adjustment also means a check-up. Should, e.g., somebody have changed the bulb and not put the new one in correctly, it will be noticed by the experienced mechanic. As a spectator, you wouldn't necessarily even notice, that e.g., the high-beam is also tested for sufficient brightness. In the meantime, the more expensive devices give out a digital evaluation of the lighting strength.
The above tip confirms your suspicions, that the newer lighting systems require special testing mechanisms. Thus, the automatic headlamp beam-range adjustment must be set to the zero position by the tester, for LED-lights, a new testing monitor is even necessary. Frontal cameras also have to be precisely aligned. Who knows what equipment the workshops are going to have to purchase for headlamps with similar attributes?
If you wish to improve your skill and intend to drive your car in Great Britain, then have a look at the pictures 3 and 4. below. There are kits available, with which one can cover a certain part of the headlamp with a sticker so that the oncoming traffic in countries where one drives on the left, is not dazzled. If you happen to have a car like the one shown in picture 1 or 2, then all you need to do is flip a switch. Having done this, you can be assured, that for the oncoming traffic, your lights won't be producing anything like a disco-light-show (see video 2). 06/14