Do the images remain when you turn on the light? Try getting a bright bedside lamp and turning it on when you see this frightening images.
One question you have to answer is do the images exist when you are fully awake or only when you are asleep and in the process of waking up?
What happens is, I will wake up (usually during the middle of the night) and I will see these things for a period of time, and get freaked out because I think they are real and then If i switch on the light they are gone. It happens all the time and it is getting quite frustrating at times. Are they hallucinations or do you have any idea what it could be?
I am not a doctor, so my ideas come from my personal experience which may include following doctor's advice specific to my problem.
I think you are in the transition between sleep and awake - if you can remain calm you may be able to determine by not turning on the lights and making the images go away with you awake mind - don't run from them confront them.
Failing that I'd leave a "night light" on to see if that squelches the images when you wake up in the otherwise dark room. I'd use a fairly bright night lite, perhaps something like a refrigerator light - 20 watt tungsten (old fashioned) bulb.
It has been my experience that the way to beat mental difficulties is to face them head-on, to beat them, show them who is in charge, you are.
The time I broke a night mare problem, many years ago as a youngster, I found a way to wake myself up before the bad stuff started. After I accomplished that my mind just gave up and quit the night mare stuff. I may have a night mare or scary dream once a year - not often, and while an old guy now I still have my fears and phobias.