lecture 2 a colorengineering
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LECTURE 2
Color Engineering
Intensity, Hue, and Saturation
Brightness, Colorfulness, and Hue
Related and Unrelated Color
Unrelated color Color perceived to belong to an area or object seen in
isolation from other colorsRelated color
Color perceived to belong to an area or object seen in relation to other colors
Brightness
Attribute of a visual sensation according to which an area appears to emit more or less light
Absolute level of the perception
Bright
Dark
Bright? White
Lightness
The brightness of an area judged relative to the brightness of a similarly illuminated area that appears to be white or highly transmitting
Related brightness (normalized)
Sample - Brightness
Colorfulness
Attribute of a visual sensation according to which the perceived color of an area appears to be more or less chromatic
Chroma
Colorfulness of an area judged as a proportion of the brightness of a similarly illuminated area that appears white or highly transmitting
Relative colorfulness As lightness can be thought of as relative
brightness
Saturation
Colorfulness of an area judged in proportion to its brightness
Colorfulness of a stimulus relative to its own brightness
Chroma Colorfulness relative to white
Colorful
Dull
Colorful?
Sample - Colorfulness
Hue
The degree to which a stimulus can be described as similar to or different from stimuli that are described as red, green, and yellow
Sample - Hue
Gray and Brown
Gray Achromatic color with low lightness
Brown Orange with low lightness
Change backgroundUnrelated colors
Hue, brightness, colorfulness, saturationRelated colors
Hue, brightness, colorfulness, saturation, lightness, chroma
Definitions in Equations
Chroma: colorfulness relative to the brightness of a similarly illuminated white
Saturation: colorfulness of a stimulus relative to its own brightness
Lightness: ratio of the brightness of a stimulus to the brightness of a similarly illuminated white stimulus
Definitions in Equations
Saturation: ratio of colorfulness to brightness
Specify Color Appearance
Brightness, lightness, colorfulness, chroma, and hue
Saturation is redundantNeed 5 out of 6 to specify color appearance
Brightness-colorfulness vs. lightness-chroma
Brightness-colorfulness matching vs. lightness-chroma matching
Example - photo Yellow school bus outside
Colorfulness high, chroma high, brightness high, lightness high
Photo of yellow school bus inside Colorfulness low, chroma high, brightness low,
lightness high Photo of yellow school bus outside
Colorfulness high, chroma high, brightness high, lightness high
Key: reflected energy
Reproduction at Higher Luminance
Reproduction at Lower Luminance
Brightness-colorfulness vs. lightness-chroma
Example - projector Overhead projector 35mm slide projector
Summary
Related and unrelated colorBrightness and lightnessColorfulness and chromaSaturationHue5 of 6 variablesBrightness-colorfulness vs. lightness-
chroma