High key lighting vs low key lighting

High key lighting is considered happy in terms of the mood set in the scene as apposed to low key lighting which attempts to set a darker and more ambiguous and threatening mood.

example #1 joker and Harvey Dent scene in dark knight (low key/high key) https://www.youtube.com/watch?v=MsLYoqjgl_Y
this shows us how using minimalistic lighting and preferably just a shimmer of natural light changes the mood. The mood of Joker and Harvey dent is sinister at heart and puts the viewer in a state of anxiousness.
On the other hand. The next scene is THE jOKER bowing up a building in his typical chaotic fun loving, blowing up mentality which utter destruction following and creates a contrast. The contrast comes in when you realise that the joker is darker in his intentions rather than his actions in this part of the movie as opposed to when his actions were darker than his intentions earlier in the film.

Example #2 alien (low key) https://www.youtube.com/watch?v=eDRLtgr2T9E
In this example the soldiers are exploring the area and stumble upon something that has no explanation. The set is scary and ambiguous, but the lighting makes it feel cut off from the rest of the world and a sense of entrapment that creates the threatening sense that you feel.

example #2 limitless(high key effect as apposed to low key) https://www.youtube.com/watch?v=xP-ZwmCPBAs
In limitless, aspiring writer who has writers block gets given a pill that "unlocks" the other 80% of his brain. This higher intelligence is emphasised by the high key lighting compared to the "dull" lighting shown when he is melancholic and unappy. The transition is quite shocking and visually appealing to have such a bright lit scene. The high key lighting also sets a happy go lucky and almost positive and able to do anything in a world with high key lighting.


iN CONCLUSION. To make a scene happy-high key lighting. To make a scene threatening-low key
The ultimate use is the contrast between one scene and another to make the feeling of one scene seem better or worse to suit the feeling of the characters.

high key