Every image or video we see has its colours altered. Annie Sneed wrote about how these changes affect your emotions:

• Warm orange-yellowey colours are friendly while blue is usually considered to be more distant.
• This is why in political ads candidates have an orange glow around them while their opponents are depicted with hues of blue.
• Green can be a mixed bag. Outdoors it’s a positive colour and so if the aim is to create a somber outdoor scene then greens are desaturated.
• Indoors however it elicits a sense of disgust and so the green is ramped up – as in The Matrix films.
• To indicate a dream sequence or a flashback contrast is added which creates a sense of distance from reality.

See what colourists do to create foreign worlds, why we have these colour associations, and visual examples here.

Source: Fast Company