Rgb and Cmy color model

RGB color stands for RED,GREEN and BLUE. This color model is used in computer monitors, television sets,
and theater. It's an additive color model.

CMYK refers to the four inks used in some color printing: cyan, magenta, yellow and key (black).

1. R G B AN D C M Y C O L O R M O DE L

2. R G B COLOR MODEL RGB color stands for RED,GREEN and BLUE. This color model is used in computer monitors, television sets, and theater. It's an additive color model. Additive color model means is that where we can combine these three basic color in various ways to get a new color. 1

3. R G B COLOR MODEL CONT. When we will combine RED+GREEN+ B LUE=WHITE Example: R G B (Red, Green ,Blue) is of 8-bit each. Thus maximum possible range by individual is 0-255 (as 2^8 = 256) 2

4. EXAMPLES RGB R(255)+G(255)+B(255) =W We get white while intersecting C (cyan) = G + B M (magenta) = R + B Y (yellow) = R + G WHITE(max) While we combined “+” means additive 3

5. A subtractive color model. CMYK refers to the four inks used in some color printing: cyan, magenta, yellow and key (black). Subtractive because, The ink reduces the light that would otherwise be reflected. Inks subtract brightness from white. Represent by value only or 1 0 = no color 1= full color 4 C M Y COLOR MODEL

6. EXAMPLES CMY “-” means subtractive C (cyan) = W - R M (magenta) = W - G Y (yellow) = W – B Key color black(max) 5

7. DIFFERENCES BETWEEN RGB AND CMY (SIGHT DIFFERENCE) 6

8. DIFFERENCES BETWEEN RGB AND CMY CONT. CMYK is a four-color mode that utilizes the colors cyan, magenta, yellow and black in various amounts to create all of the necessary colors RGB is an additive type of color mode that combines the primary colors, red, green and blue, in varying levels, to create a variety of different colors. RGB is vibrant Whereas CMYK is not vibrant but good for reading 7

9. DIFFERENCES BETWEEN RGB AND CMY CONT. In RGB , when all three colors are combined and displayed to their full extent, the result is a pure white. In CMYK , when the first three colors are added together, the result is not pure black, but rather a very dark brown. CMYK is the primary color model used by color printers. RGB is the typical color model used on electronic devices such as computers, theaters etc. 8

10. CONVERSION POLICY ( RGB TO CMYK ) There is a core formula if we want to convert. The R,G,B values are divided by 255 to change the range from 0..255 to 0..1: R ' = R /255 G ' = G /255 B ' = B/255 9

11. CONVERSION POLICY ( RGB TO CMYK ) CONT. The black key (K) color is calculated from the red (R'), green (G') and blue (B') colors: K = 1-max( R ', G ', B ') The cyan color (C) is calculated from the red (R') and black (K) colors: C = (1- R '- K ) / (1- K ) The magenta color (M) is calculated from the green (G') and black (K) colors: M = (1- G '- K ) / (1- K ) The yellow color (Y) is calculated from the blue (B') and black (K) colors: Y = (1- B '- K ) / (1- K ) 10

12. EXAMPLE Lets think There is RGB value for violate( 100 , 50 , 150 ) We want to convert it into CMYK According to formula…. R’ =100/255 =0.392 G’ =50/255 =0.196 B’ =150/255 =0.588 Lets find the key for CMY K =(1-0.588)=0.412 [Because this the largest value among given result] (1-K) =0.588 [Will require later] 11