Creating histograms

A histogram shows the statistical frequency of data distribution within a data set. In the case of remote sensing, the data set is an image, the data distribution is the frequency of pixels in the range of 0 to 255, which is the range of 8-byte numbers used to store image information on computers. In an RGB image, color is represented as a 3-digit tuple with (0,0,0) being black, and (255,255,255) being white. We can graph the histogram of an image with the frequency of each value along the y-axis and the range of 255 possible pixel values along the x-axis.

Remember in Chapter 1, Creating the Simplest Possible Python GIS, when we used the Turtle graphics engine included with Python to create a simple GIS? Well we can also use it to easily graph histograms. Histograms are usually a one-off product that makes a quick script, like this example, great. Also histograms are typically displayed as a bar graph with the width of the bars representing the size of grouped data bins...