A color model is a multidimensional representation of the color spectrum. The most relevant color spectrums are RGB, HSV, HSL and CMYK. A color model can be represented as a 3D surface (e.g. for RGB) or go into much higher dimensions (such as CMYK). By adjusting the parameters of these surfaces, we can obtain different colors that we see in the color spectrum around us.
HSV:
An HSV color model is the most accurate color model as long as the way humans perceive colors. How humans perceive colors is not like how RGB or CMYK make colors. They are just primary colors fused to create the spectrum. The H stands for Hue, S stands for Saturation, and the V stand for value. Imagine a cone with a spectrum of red to blue from left to right, and from the centre to the edge, the color intensity increases. From bottom to up, the brightness increases. Hence resulting white at the center up layer. A pictographic representation is also shown below.
- Hue: Hue tells the angle to look at the cylindrical disk. The hue represents the color. The hue value ranges from o to 360 degrees.
|
Angle (in degree) |
Color |
|---|---|
|
0-60 |
Red |
|
60-120 |
Yellow |
|
120-180 |
Green |
|
180-240 |
Cyan |
|
240-300 |
Blue |
|
300-360 |
Magenta |
- Saturation: The saturation value tells us how much quantity of respective color must be added. A 100% saturation means that complete pure color is added, while a 0% saturation means no color is added, resulting in grayscale.
- Value: The value represents the brightness concerning the saturation of the color. the value 0 represents total black darkness, while the value 100 will mean a full brightness and depend on the saturation.
Advantages:
The advantage of HSV is that it generalizes how humans perceive color. Hence it is the most accurate depiction of how we feel colors on the computer screen. Also, the HSV color space separates the luma from the color information. this allows us to perform the operations mentioned above in the applications section, as the histogram equalization will only be required for intensity values.
Applications:
- HSV model is used in histogram equalization.
- Converting grayscale images to RGB color images.
- Visualization of images is easy as by plotting the H and S components we can vary the V component or vice-versa and see the different visualizations.