Image processing is a method to perform some operations on an image, in order to get an enhanced image or to extract some useful information from it. It is a type of signal processing in which input is an image and output may be image or characteristics/features associated with that image. Nowadays, image processing is among rapidly growing technologies. It forms core research area within engineering and computer science disciplines too.

Image processing basically includes the following three steps:

  • Importing the image via image acquisition tools;
  • Analysing and manipulating the image;
  • Output in which result can be altered image or report that is based on image analysis.
Basic Image processing system
Basic Image processing system

There are two types of methods used for image processing namely, analogue and digital image processing.

Analogue image processing

Analog image processing is done on analog signals. It includes processing on two dimensional analog signals. In this type of processing, the images are manipulated by electrical means by varying the electrical signal. The common example include is the television image. And also analogue image processing can be used for the hard copies like printouts and photographs. Image analysts use various fundamentals of interpretation while using these visual techniques.

Digital image processing has dominated over analog image processing with the passage of time due its wider range of applications.

Digital image processing

Digital image processing is the use of a digital computer to process digital images through an algorithm. The three general phases that all types of data have to undergo while using digital technique are pre-processing, enhancement, and display, information extraction.

Digital image processing has many advantages over analog image processing.

Advantages of Digital Image Processing

  • Image reconstruction (CT, MRI, SPECT, PET)
  • Image reformatting (Multi-plane, multi-view reconstructions)
  • Fast image storage and retrieval
  • Fast and high-quality image distribution.
  • Controlled viewing (windowing, zooming)

Disadvantages of Digital Image Processing

  • It is very much time-consuming.
  • It is very much costly depending on the particular system.
  • Qualified persons can be used.


  1. ACQUISITION– It could be as simple as being given an image which is in digital form. The main work involves:
    a) Scaling
    b) Color conversion(RGB to Gray or vice-versa)
  2. IMAGE ENHANCEMENT– It is amongst the simplest and most appealing in areas of Image Processing it is also used to extract some hidden details from an image and is subjective.
  3. IMAGE RESTORATION– It also deals with appealing of an image but it is objective(Restoration is based on mathematical or probabilistic model or image degradation).
  4. COLOR IMAGE PROCESSING– It deals with pseudo color and full color image processing color models are applicable to digital image processing.
  5. WAVELETS AND MULTI-RESOLUTION PROCESSING– It is foundation of representing images in various degrees.
  6. IMAGE COMPRESSION-It involves in developing some functions to perform this operation. It mainly deals with image size or resolution.
  7. MORPHOLOGICAL PROCESSING-It deals with tools for extracting image components that are useful in the representation & description of shape.
  8. SEGMENTATION PROCEDURE-It includes partitioning an image into its constituent parts or objects. Autonomous segmentation is the most difficult task in Image Processing.
  9. REPRESENTATION & DESCRIPTION-It follows output of segmentation stage, choosing a representation is only the part of solution for transforming raw data into processed data.
  10. OBJECT DETECTION AND RECOGNITION-It is a process that assigns a label to an object based on its descriptor.