Prof. Muhammad Saeed

FUUASTDept. Comp. Sc. & IT2 Wavelength Note that the rainbow does not contain any magenta. It is nonspectral. Color Models:

FUUASTDept. Comp. Sc. & IT3 Newtons Color Wheel Replaced Aristotles color model based on light and darkness. Color Models:

FUUASTDept. Comp. Sc. & IT4 Color Models: Spectrum ultraviolet light Wavelength (nm) Seen in physics, physical phenomena (rainbows, prisms, etc) 1 Dimensional color space Infrared light

FUUASTDept. Comp. Sc. & IT5 Sensitivity and Models

FUUASTDept. Comp. Sc. & IT6 Tristimulus Color Theory Any color can be matched by a mixture of three fixed base colors (primaries) Eye has three kinds of color receptors called cones Eye also has rods (low light receptors) Color Receptors in Eye Wavelength λ (nm) Fraction of light absorbed by each type of cone Color Models:

FUUASTDept. Comp. Sc. & IT7 Wavelength is in nanometers Color Models:

FUUASTDept. Comp. Sc. & IT8 Traditional, Artistic: RGB CMY CMYK HSV HSL Perceptually Based: XYZ (Tristimulus) Xyz Hunter-Lab CIE-L*ab CIE-L*CH° CIE-L*ab CIE-L*uv Color Models:

FUUASTDept. Comp. Sc. & IT9 Color Models: Tints, Tones and Shades: White Pure Color Black Shades Tones Grays Tints

FUUASTDept. Comp. Sc. & IT10 Additive Primaries: (r,g,b) (1,0,1) (0,0,1 ) magentamagenta whitewhite (1,1,1) (0,1,0)greengreen (1,1,0)yellowyellow (0,1,1) cyancyan blueblue (1,0,0) redred Color Models:

FUUASTDept. Comp. Sc. & IT11 Color Models: (0,0,1 ) blueblue (1,0,1) magentamagenta (0,1,1) cyancyan (0,1,0) (1,1,0) yellowyellow (1,0,0) redred whitewhite (1,1,1) (0,0,0) blackblackgraygray RGB Model: greengreen

FUUASTDept. Comp. Sc. & IT12 (0,0,1 ) blueblue (1,0,1) magentamagenta (0,1,1) cyancyan (0,1,0) greengreen (1,1,0) yellowyellow (1,0,0) redred (1,1,1) whitewhite Color Models:

FUUASTDept. Comp. Sc. & IT13 Looking at color cube along major diagonal Color Models:

FUUASTDept. Comp. Sc. & IT14 (0,0,1) Color Models: (1,1,0) yellowyellow (0,1,0) greengreen (0,1,1) cyancyan blueblue (1,0,1) magentamagenta (1,0,0)redred blackblack (0,0,0) Subtractive Primaries: (r,g,b)

FUUASTDept. Comp. Sc. & IT ˚ 0˚0˚ V S H ˚ yellowyellow greengreen cyancyan redred magentamagenta blueblue Introduced by Albet Munsell, late 1800s. He was an artist and scientist Hue: Color Saturation/Chroma: Strength of a color –Neutral gray has 0 saturation Brightness/Value: Intensity of light emanating from image Color Models: H S V MODEL

FUUASTDept. Comp. Sc. & IT16 Saturation Color Models:

FUUASTDept. Comp. Sc. & IT17 James C. Maxwells Color Model magentamagenta blueblue cyancyan greengreen redred yellowyellow unsaturated cyan whitewhite Color Models:

FUUASTDept. Comp. Sc. & IT S L 0˚0˚ 0.0 H whitewhite blackblack redred Color Models: HLS Model (Hue, Lightness, Saturation)

FUUASTDept. Comp. Sc. & IT19 Color Models: HSV to RGB

FUUASTDept. Comp. Sc. & IT20 Color Models: RGB to HSV

FUUASTDept. Comp. Sc. & IT21 Color Models: CIE* Color Space ( X, Y, Z ) represents an imaginary basis that does not correspond to what we see Define the normalized coordinates: x = X / ( X + Y + Z ) y = Y / ( X + Y + Z ) z = Z / ( X + Y + Z ) * Commission Internationale de l'Êclairage

FUUASTDept. Comp. Sc. & IT22 x + y + z = 1 x = X / ( X + Y + Z ) y = Y / ( X + Y + Z ) z = Z / ( X + Y + Z ) z y x The projection of the plane of the triangle onto the (X,Y) plane forms the chromaticity diagram that follows. Color Models: Colors CIE Color Space of Visible Colors

FUUASTDept. Comp. Sc. & IT23 Color Gamuts: CIE Color Chart cyan magenta red blue green yellow whitewhite Color Models:

FUUASTDept. Comp. Sc. & IT24 ideal red ideal blue ideal green redred blueblue greengreen cyan yellow whitewhite 400 nm 490 nm 500 nm 510 nm 540 nm 560 nm 580 nm 700 nm 600 nm 520 nm Color Gamuts: CIE Color Chart Color Models:

FUUASTDept. Comp. Sc. & IT25 Color Gamuts: CIE Color Chart Color Models:

FUUASTDept. Comp. Sc. & IT26 R B G The Color Gamuts of different displays and printers are not likely to match. Printers usually have smaller gamuts. Color Gamuts: CIE Color Chart Color Models:

FUUASTDept. Comp. Sc. & IT27 Color Models: CIE Chromaticity Diagram:

FUUASTDept. Comp. Sc. & IT28 C2C2 C3C3 C1C1 The additive colors C 1 and C 2 combine to form C 3 on the line connecting C 1 and C 2. Color Gamuts: CIE Color Chart Color Models:

FUUASTDept. Comp. Sc. & IT29 Color monitors are based on adding three the output of three different light emitting phosphors. The nominal position of these on the CIE diagram is given by : x y z Red Green Blue Color Models: Reproducible colors:

FUUASTDept. Comp. Sc. & IT30 Color Models: The monitor RG B representation is related to the CIE colors by the equation: RGB to CIE: Color (RGB) to Gray Transformation: Red *= 0.33, Green *= 0.56, Blue *= 0.11

FUUASTDept. Comp. Sc. & IT31 CIE Chromaticity Diagram Color Models: CIE Model (Commission Internationale de I Eclairage):

FUUASTDept. Comp. Sc. & IT32 Color Models: Gamma Correction:

FUUASTDept. Comp. Sc. & IT33