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Cool Colors

Definition:
Blues, greens, and purples are considered cool colours. In aerial perspective cool colours are said to move away from you, or appear more distant.
If you compare different blues (or greens or purples), you’ll see that there are also warm and cool versions of each of these colors, relative to each other.

Tone or Value

Definition:
The lightness or darkness of a color, rather than what the actual color is (e.g. cadmium red or Prussian blue).
Using a monochrome filter makes it easy to compare tones in a subject.

Aerial Perspective

Definition:
The term for how atmospheric conditions influence our perception of objects in the distance. As objects get closer to the horizon (or further away), they appear lighter in tone, less detailed, and bluer or cooler in color.
It’s something that’s easier to understand visually than in words. Take a look at the phototowards the right [...]

Monochrome Filter

Definition:
A monochrome filter is a filter made from a piece of plastic in a primary color. Looking through it at objects reduces the colors you’re seeing to tones of whatever color the filter is, enabling you to easily see and compare how light or dark the tones or values are.
Dark red is generally used [...]