Introduction:

What is an Image?

• A Two Dimensional Data Structure made up from picture elements (pixels).
  
  

What is Image Processing?

• Performing operations on images.

Image Characteristics

• Large amount of data (~1 million numbers for a high quality picture).
• Pixels are related to their neighbours.
• Most of the data is redundant (i.e. it contains little information).

Image Processing Characteristics

• Many Simple Operations.
• It is only recently that sufficient processing power has become available; users may now perform image processing on relatively small computers.
• A working model is available:
  The Human Visual System.

Image Processing Operations

Image Coding

Image coding reduces the storage requirement for an image by removing redundant information. This may be done in two ways.

Exact Coding

The image may be reconstructed exactly. Standard coding techniques may be used.
Compression of 2:1 is typically achieved.

Fidelity Coding

• The image may be reconstructed so that a human observer notices little or no degradation.
  Compression of 50:1 is typically achieved.

Applications of Image Coding

• Digital Cameras.
• CDROM MPEG Movies.
• Video on Demand.
• Video-phones.
• Video-conferencing.
• Hypermedia Documents.

Image Enhancement

An image may need to be processed so that it may be viewed. For example, an X-ray image may be displayed with greater contrast in some regions so that very faint features can be seen.

Applications of Image Enhancement

• Medical Imaging.
• Scientific Visualisation.
• Publishing.
• Astronomy.
• Microscopy.
• Particle Physics.

Image Restoration

If an image has known faults then these may often be corrected. A blurred image may be 'deblurred' or a noisy image may have noise removed. Restoration often relies on knowledge of the process that caused the degradation.

Image Segmentation

Sometimes similar areas in an image must be identified, for example from an aerial photograph the land and the sea may need to be segmented.

Feature detection

Often, only part of an image is of interest.

Feature detection creates an image that contains information about the presence of certain types of features. Edges are common features.

Feature Detection using the Hough Transform

Applications of Image Restoration, Segmentation and Feature Detection.

• Remote Sensing.
• Medical Imaging.
• Character Recognition.
• Data Analysis.
• Computational Vision.
• Feature Location.
• Gesture recognition.