Wednesday, November 13, 2013

What is Digital Image Processing?

I will be using simple language to explain the concepts. To understand Digital Image Processing, let us see each word individually.


For standard definitions about image you can refer to the wikipedia page : Image Definition  . If you have any difficulty in understanding that definitions, here is my definition for the image.

"Image" is the visual representation of information. That's it. Short and simple. If you are a person who isn't sure what the word "information" means, read further. "Information" is description of something or anything. To understand what the "visual representation" means here, read the below example.

 I already told that "Information" is description of something. For example, my physical description is "Male, Young, Average height, Short hair, and Casually dressed". Here I have described my physical appearance in text, this is said to be representing an information through text. 

The same information if I had communicated to someone through my speech, it is said to be representing an information through audio. 

Similarly, the same information can be represented visually if I take a picture of myself and post it here.

The above image also conveys the same information i.e)  "Male, Young, Average height, Short hair, and Casually dressed" but it is represented visually. So we have now learned what is an image in an unconventional way.


A digital image is a numeric representation of a two-dimensional image. It will have pixel values are numerical.

What is pixel ?

Pixel is a smallest sample in an image. To understand what is pixel, you must know how the images are captured digitally(without using film rolls). Watch the below video:

 Youtube Link: How to capture image digitally

I believe you have seen the above mentioned video. The smallest unit in the CMOS sensor is said to be the picture element. The term PIXEL is derived from this "PICture ELement". When the light reflected from the object that has to be captured hits this picture element in the CMOS sensor, the light energy is converted into electrical signals then this electrical signal converted into digital data (numerical value) using Analog to Digital Converter while saving to the memory card. So the image is now captured digitally.


Now that we have captured an image digitally. We to do perform some operation on the captured image to improve its perceived quality (It is said to be Image enhancement), reduce the size for storage and transmission (Image Compression) and etc.

Here is the block diagram for different processes that are done for digital images:

I hope this give you the basic understanding of Digital Image Processing.

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