Hi all! 
I currently working on a horror game, and I want to add a timed flashing image script, a fullscreen image will shown in every 3 minute, or more or less or random.
Or a triggered one, when my character go trough a trigger zone, a fullscreen image will shown up for one second.
Can you guys help me out? 
Cheers!
Use a coroutine.
When onTriggerEnter is called, start a coroutine that shows the image, and then removes it. you can choose to make it flicker through a yield statement multiple times. If you’re new to coroutines, I have a video about them in my tutorial misc. series. (Link in sig)
Thank you! I’m going to check it out.
Add a plane into scene.
Place it in front of of the active camera.
Parent the plane to the camera.
Create a material and add photo you want to show players.
Drag material onto the plane.
Create a script which activates/deactivates the mesh renderer of the plane making it visible and invisible.