Week 9 - Image Processing

An image capture system contains a lens and a detector. In digital photography the detector is often a charge coupled device (CCD), a linear or matrix array of photosensitive electronic elements.

Pixelization can be seen with the unaided eye if the sensor array is too low. Increasing the number of cells in the sensor array, increases the resolution of the image captured.

Before the light is collected by the lens is focuses on to the sensor array, it is passed through an optical low pass filter that serves to:

• Exclude any picture data, which is beyond the sensor's resolution.

• Compensate for false colouration 

• Reduce infrared and other non-visible light. 

A pixel is the smallest digital element manipulated by image processing software.

Each pixel is individually coloured but since they are of finite size, pixel only approximate the actual colouring of a subject. Thus bit maps often show blocky areas or jagged lines under close examination.



Four common categorisation of DIP operations are analysis, manipulation, enhancement and transformation.

• Analysis operations provide information on photometric features of an image e.g. colour count, histogram

• Manipulation operations change the content of an image e.g. flood fill, crop

• Enhancement operation attempt to improve the quality of an image in some sense e.g. heighten contrast, edge enhancement 

• Transformation operations alter the image geometry e.g. rotate, skew