Image

A group of width pixels horizontally and height pixels vertically is called an Image. There are two types of Images.
1) Grayscale Image
2) Color Image

Grayscale :
It is a monochrome version of a color Image. Color varies from Black, Dark Gray, .., Light Gray, White. Pixel value of 0 represents Black and Pixel Value of 255 represents white. Values in between 0 and 255 varies from Dark Gray to Light Gray.

Color Image :
A Pixel is combination of Red, Green and Blue(RGB). Therefore the size of the Image will be (width * height * 3) bytes. Each (width * height) bytes for Red, Green and Blue respectively.