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BASIC IMAGE ANALYSIS

1. Introduction

DIVA has some basic image analysis functions. These are outlined here, but more detailed information and examples may be accessed by following the corresponding links.

2. Statistics

Some statistics of the original image ("Tools" -> "Statistics...") or an extracted-ROI (button on GUI) image are calculated and displayed in the DIVA STATS GUI. These are;

• bottom left coordinates ([0,0] for entire image)
• top right coordinates ([width,height] for entire image)
• area (number of pixels)
• minimum value
• maximum value
• mean value
• variance
• standard deviation

A more detailed description of this function is here.

3. Histogram

In an image processing context, the histogram of an image normally refers to a histogram of the pixel intensity values. This histogram is a graph showing the number of pixels in an image at each different intensity value found in that image. The histogram is displayed in the DIVA HIST GUI.

A more detailed description of this function is here.

4. Image Math

An image may be operated on by either another image or a constant. If both operands are images, then they must be of the same size. Operations include addition, subtraction, division and multiplication. Also, the average of 2 images may be calculated.

Images are loaded into the DIVA MATH GUI by selecting "View" -> "Save image". This operation stores images in memory (by default images are not stored in memory, but are instead accessed from disc).

In order to access the DIVA MATH GUI select "Tools" -> "Image Math...". If no images have been stored, then this will be unavailable.

A more detailed description of this function is here.

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E-mail me at j.a.rainnie@rl.ac.uk

Copyright � 2003 John Rainnie
Last updated January 2003