If you look at the palm of your hand, you will see that it is concave. Generally you therefore want the majority of the handle to have middle of the curve up, ends of the curve down.
In the top handle it is clear that this has been done.
In the bottom handle it is less clear, as the majority of the handle seems to be flat. What curves there are at the end would suggest from my logic that it's been installed upside-down... but its installation doesn't look wrong to me. In fact it looks right - the curves at the end look more decorative than practical to me.
I'd therefore suggest that I'd install the handle however it was designed. Both handles in your images look to me to have been installed the way up they have been designed.
There are sometimes other clues as to which way up a handle is designed to be installed.
In the top handle you can see that the handle is narrower at the bottom than the top; this is therefore installed the correct way up. You wouldn't want the the top of the handle digging into your hand as you pushed the handle down, you want your hand to land on a nice flat surface. This helps the confidence that the top handle is installed correctly, but it unfortunately doesn't help with the bottom handle, which is the one I'm less sure of!
Sometimes the top face of a handle isn't horizontal, but is at an angle sloping down towards the door (i.e. sloping away from you). The reason for this is that your arm is generally pointing downwards (your shoulder is higher than the handle, unless you're a small child) and hence it is less comfortable (requires less angle in your wrist) to not have to rotate your hand to horizontal. This doesn't apply to either handle you have pictured.