ipppt-1 color model image processing ip ppt

IMAGE PROCESSING
(IT9018)
Narayn Furmalkar (19)
Rohit Kulkarni (33)
Rutuja More (37)
Tukaram Shinde (49)
Akash Sirsat (51)

INDEX
1. Color Model Fundamentals
2. Color model characterstics
3. RBG color model
4. CMY color model
5. HSI color model
6. Conclusion
7. References

COLOR FUNDAMENTALS:
1. Colors are seen as variable combinations of the Primary colors of light:
- Red (R), Green (G) and Blue (B).
2. The Primary colors can be mixed to produce Secondary colors:
- Magneta (Red+Blue), Cyan (Green+Blue) and Yellow (Red+Green).
3. Mixing the three primaries, or a Secondary with its opposite Primary color,
produces white light.
4. RGB colors are used for color TV, monitors, and video cameras.
Fig. Primary and Secondary colors of light

5. However the Primary colors of pigments are Cyan (C), Magneta (M) and
Yellow (Y), and the Secondary colors are Red, Green and Blue.
6. A proper combination of the three pigment primaries, or a Secondary with
its opposite Primary, produces black.
7. CMY colors are used for color printing.
Fig. Primary and Secondary colors of pigment

COLOR CHARACTERISTICS:
The Characteristics used to distinguish one color from another are:
• Brightness: means the amount of intensity (i.e. color level).
If we talk about practical example, this is what we see in the
movies made before the 1930s.
• Hue: represents dominant color as perceived by an observer.
• Saturation: refers to the amount of white light mixed with a hue.
Hue and Saturation, together are called Chromaticity. Therefore,
a color may be characterized by its chromaticity and intensity.

COLOR MODELS:
- In Digital Image Processing, there are multiple color models present.
- The purpose of the color model is to facilitate the specifications of
colors in some standard, generally accepted way.
- A color model is a specification of a co-ordinate system and a subspace
within that system where each color is represented by a single point.
- Different types of color models are used in multiple fields like in hardware,
in multiple applications of creating animation, etc.
• In Digital Image Processing, the hardware-oriented models that are commonly used
are the RGB model for printers and color monitors.
• CMY(cyan, magenta, yellow) and CMYK(cyan, magenta, yellow, black) models are
used for color printing.
• HSI(hue, saturation, intensity) deals with colors as humans interpret.
- Let’s discuss each color model and its application. We will start with the
most popular model that is the RGB model

1. RGB MODEL:
 It is an additive color model.
 It uses primary colors i.e. red, green and blue
 It uses light to display colors
Fig. RGB Color Cube

Applications of RGB Color Model-
- The RGB model is widely used in the representation and display of images
in electronic systems like computers and televisions.
- It is also used in conventional photography as well.
- Image scanner which scans images and converts it to a digital image mostly
supports RGB color.
- It is used in web graphics.

2. CMY MODEL:
- This model contains the secondary colors. In this model, any
secondary color when passed through white light will not reflect the
color from which a combination of colors is made.
- For example- when cyan is illuminated with white light, no red light
will be reflected from the surface which means that the cyan subtracts
the red light from the reflected white light (which itself is composed of
red, green and white light).
Eq.1
- The formula given in equation 1 is for inter-conversion of RGB and
CMY models.

Fig. Input Image
Fig. C, M and Y components of an image

Applications of RGB Color Model-
- It is used in color printing as it uses
colored inks.
- It is used in most commercial printing
like magazines, books, etc.

3. HSI MODEL (Hue, Saturation, Intensity):
- It is a very important and attractive color model because it represents the colors
the same way as the human eye senses colors.
- We have already read about Saturation and Intensity.
Now, what is Hue?
- Hue is a color component that describes a pure color (pure yellow,
orange or red).
- Saturation component represents the measure of the degree to which
color is mixed with white color.
0 degree – Red
120 degree – Green
240 degree – Blue
60 degree – Yellow
300 degree – Magenta

Intensity
Range is [0, 1]
0 means white
1 means black
- The formula for conversion of RGB to HSI is quite complicated as compared to
other color models.
- The angle from the red axis gives the Hue, the length of the vector is the
saturation and the intensity is given by the position of the plane on the vertical
intensity axis.
- The biggest application of this model is that it represents colors similarly to
how the human eye senses colors.
Fig. HSI Model

Conclusion
 So far we’ve studied the three most popular color models
 A color model is a specification of a co-ordinate system and a subspace
within that system where each color is represented by a single point.
 Each color model has it’s own application
 Some models are additive while others are substractive
 These models can be interconverted

References
 https://users.cs.cf.ac.uk/Dave.Marshall/Multimedia/node190.html
 https://www.geeksforgeeks.org/computer-graphics-the-rgb-color-model/
 https://www.cronj.com/blog/color-space-image-processing/
 https://www.sciencedirect.com/science/article/pii/S2046043016300879
 https://www.slideshare.net/shkulathilake/color-and-color-models-
43400611

ipppt-1 color model image processing ip ppt

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