Colour Image Processing
Color image is a digital image that includes color information for each pixel.
For visually acceptable results, it is necessary to provide three samples. for each pixel, which are interpreted as coordinates in some color space. The RGB color space is commonly used in computer displays, but other spaces such as YCbCr, HSV, and are often used in other contexts. A color image has three values (or channels) per pixel and they measure the intensity and chrominance of light. The actual information stored in the digital image data is the brightness information in each spectral band.
The HSI color space
The HSI color space is very important and attractive color model for image processing applications because it represents colors similarly how the human eye senses colors. The HSI color model represents every color with three components: hue( H ),saturation( S ), intensity ( I ). The below figure illustrates how the HSI color space represents colors:-
The Hue component describes the color itself in the form of an angle between [0,360] degrees. 0 degree mean red, 120 means green 240 means blue. 60 degrees is yellow, 300 degrees is magenta.
The Saturation component signals how much the color is polluted with white color. The range of the S component is [0,1].
The Intensity range is between [0,1] and 0 means black, 1 means white.