This page is about intensity measurements.  We will explain two ways of quantitating the total intensity of an image.
1.  The sum of all the intensities or the mean intensity value.   The mean is the sum divided by the area.
2.  Histogram measurement of intensities which plots the distribution of pixel values.

Flat	Gradient	Split

These three images are very different or absolutely identical depending how we approach their analysis.

Visually, they are very different.  [Missing is an example of noise with a Gaussian distribution.]

The images are grayscale with a range from 0 to 255.  The mean intensity of each image is 128.

But the standard deviation varies widely.  In the case of wide standard deviation, a histogram analysis may be more telling.

Page last revised 2 Jun 2000