Low Key

• Darker values than the standard range
• Values are compressed: dark (black) to mid tone
• Lightest lights are only in the mid tone range
• Color: Richer colors, a lot of browns
• Atmosphere: Moody, mystery, drama, subdued
• Darkly lit scenes w/ low contrast, still life
• Examples: Dutch / Flemish Painters

High Key

• Lighter values than the standard range
• Values are compressed: mid tone to light (white)
• Darkest darks are only in the mid tone range
• Colors: Appears more vibrant / colorful
• Atmosphere: spring, happy, airy, bright, soft, calm
• Relies more on color than value
• Great for landscapes / environment scenes
• Examples: Claude Monet / Impressionists

Sources:

• Schoolism, Digital Painting Workout, L4-5, by Wouter Tulp (Paid Course)
  https://schoolism.com/s/sub/course/lessons/16/580

• Watercolor Affair, Examples of Value in Art, by Anthony Roebuck
  https://www.watercoloraffair.com/examples-of-value-in-art/?tva_skin_id=32

• Draw Paint Academy, How to Paint in a High Key, by Dan Scott
  https://drawpaintacademy.com/high-key-paintings

• High Key vs. Low Key by Shawn Dell Joyce
  https://www.shawndelljoyce.com/post/high-key-vs-low-key

Photo References:

• Cynthia Nixon Promotional Photo 1979

• Greene County Barn