Monday, August 25, 2014

What is an Image and Image Processing?


An image is a still representation of any worldly physical thing,be it a person or an object.It  depicts our  visual perception.In Digital representation an image is a rectangular grid of pixels.An image,therefore,has a definite height and width measured in pixels.

Image may be 2-D (a photograph) or 3-D (statue or hologram). It may be volatile (like the one formed in front of a mirror) or fixed (like the one recorded on a textile).


Pixels are the smallest unit of an image or the building blocks of an image,similar to the cells that make up a human body.

A Pixel is a square shaped structure.Each pixel has some color intensity. A pixel conveys information about the image in the form of the colour intensities that it consists of. The colors talked about here are the primary colors: RED,GREEN,BLUE. All other colors are formed from these colors only.

Color intensities in a pixel are  represented in the form of bits.Each of the three RGB colors have intensities in the range 0-255, i.e., 8 bits are used for each color in a single pixel. In addition to these (8*3=) 24 bits, 8 bits are used for transparency in an image.

The higher the number between 0 and 255,the more will be the intensity of the color and the brighter the color will be.


An image is represented in the form of pixel values. Suppose an image has 1024 pixels row wise and 1024 pixels column wise, then the size of that image will be 1024x1024, and total number of pixels will be (1024*1024=) 1048576. 


Colored Image: An image having matrices for all the three colors .

Monochrome Image: An image having only one color.

Black and White Image: An image having matrix of only binary values i.e.,0 and 0 showing black color and 1 showing white.

Gray scale Image: An image having shades of gray only (neither complete black nor complete white). The new matrix in this type of image is formed by taking the average of the three color intensities.



Image Processing includes different processes that can be performed on an image in order to enhance the quality of an image. These processes can be:

1.Removal of noise.
2.Extraction of only text from the image.
3.Changing the intensity of an image.
4.Adjusting the contrast of an image.