XYZ Color Model
- The set of CIE primaries is generally referred to as XYZ Color Model or (X, Y, Z) color model.
- X, Y, Z represents vectors in a three dimensional, additive color space.
- Any color 𝐶𝜆 is a combination of three primary colors as 𝐶𝜆 = 𝑋𝑋 + 𝑌𝑌 + 𝑍𝑍
- Where X, Y, Z, is the amount of standard primary need to combine for obtaining color 𝐶𝜆.
- Also, If we normalize it then.
- X=X/(X+Y+Z), Y=Y/(X+Y+Z), Z=Z/(X+Y+Z)
- With 𝑥 + 𝑦 + 𝑧 = 1
- Now we can represent any color with x,y only as z we can find z=1-x-y.
- X and y called chromaticity values because they depend only on hue and purity.
- Now if we specify colors with the only x, and y values we cannot find amount X, Y, and Z.
- So we specify color with x, y, and Y and rest CIE amount calculated as X=(x/y).Y and Z=(z/y).Y
- Where z=1-x-y
RGB Color Model: XYZ Color Model
- Based on tristimulus theory of vision our eye perceives color through stimulating one of three visual pigments in the cones of the retina.
- These visual pigments have peak sensitivity at red, green and blue color.
- So combining these three colors we can obtain the wide range of color this concept is used in RGB color model.
- As shown in figure this model represented as the unit cube.
- Origin represents black color and vertex (1,1,1) is white.
- The vertex of the cube on the axis represents primary color R, G, and B.
- Also, In XYZ color model any color intensity obtained by addition of primary color. 𝐶𝜆 = 𝑅𝑅 + 𝐺𝐺 + 𝐵𝐵
- Where R, G, and B amount of corresponding primary color
- Since it bounded in between unit cube it values vary in between 0 to 1 and represented as triplets (R, G, B). For example, a magenta color represented with (1,0,1).
- Moreover, Shades of gray represented along the main diagonal of a cube from black to a white vertex.
- For halfway gray-scale, we use triplets (0.5,0.5,0.5).