Colours

Introduction to Color

  • Colors in the visible spectrum depend on light.

  • Each color has a distinct wavelength; red (longest) and violet (shortest).

  • Color perception is an event triggered in the observer, not fixed to objects.

White Light and Color Perception

  • Dispersion of white light through a prism leads to the rainbow spectrum: Red, Orange, Yellow, Green, Blue, Indigo, Violet

  • Color is experienced solely through vision; it cannot be heard, smelled, touched, or tasted.

Understanding Color

  • Importance of Color:

    • Influences daily life, emotions, nature, art, decoration, and clothing.

  • Components of Color Vision:

    • Involves a light source, a detector (eye), and typically a medium.

Types of Photoreceptors in Humans

  • Rods vs. Cones:

    • Rods:

      • Active in low light (scotopic vision)

      • No color perception, low spatial acuity.

    • Cones:

      • Operate in bright light (photopic vision).

      • Responsible for color vision and high spatial acuity.

      • There are three types of cones:

        • Short (S-cones - blue)

        • Medium (M-cones - green)

        • Long (L-cones - red)

Color Detection

  • Each cone detects a range of colors; sensitivity varies by cone type.

  • Overlapping receptor responses enable perception of millions of colors.

    • Example: Yellow results from stimulation of both M-cones and L-cones.

Color Deficiencies

  • Normal vision relies on L-cones, M-cones, and S-cones.

  • Color deficiencies often affect L and M cones:

    • Protanopia: L-cone deficiency (red blindness)

    • Deutanopia: M-cone deficiency (green blindness)

    • Tritanopia: S-cone deficiency (blue blindness) - rare.

  • About 8% of men and 0.5% of women have color deficiencies.

Color Vision in Animals

  • Dichromatic vs. Monochromatic Vision:

    • Humans (trichromatic), dogs (dichromatic), and rodents (monochromatic).

  • Dogs excel in night vision, compensating for limited color perception.

Afterimages and Complementary Colors

  • Afterimages: Visual images remain after stimuli removal, often observed as complementary colors.

  • Example: Staring at a bright light will create a blue afterimage if the light is yellowish.

  • This concept is illustrated by the opponent colors in color theory.

Opponent Process Theory of Color Vision

  • Suggests that color perception is managed by opposing receptor complexes:

    • Red-Green, Blue-Yellow, Black-White complexes.

  • Only one color of a pair can be perceived at a time (e.g., no greenish-red).

Color Characteristics**

  • Hue: Name of a color (e.g., red, blue).

  • Value: Lightness/darkness of a color.

    • Value scale: White -> Black (with nine typical steps).

  • Intensity (Chroma): Brightness/dullness of color, indicating its purity.

Color Mixing and Color Theory

  • Additive Color Mixing: Using light (RGB: Red + Green = Yellow).

  • Subtractive Color Mixing: Using pigments (RYB).

  • Complementary Colors: Opposite colors on the spectrum that neutralize each other.

Emotional Effects of Colors

  • Colors influence mood and perception:

    • Warm colors (reds, oranges) are stimulating and advance.

    • Cool colors (blues, greens) are calming and receding.

  • Use in design can create spatial illusions and seasonal feelings.

Practical Applications of Color in Design

  • Light colors can make spaces appear larger; dark colors can create a more intimate setting.

  • Select colors based on value to enhance visibility and harmony in designs.