From the Processor menu select Classify…. In the Set Classification Specifications dialog
box which appears, select the √ near Image Selection under Classify to de-select it since,
during this pass, it is desired to classify only the training fields in order to obtain an initial
estimate of the quality of the class definition and training.
Note that under Write classification results to: One can also select the Disk File button
causing a disk file version of the results to be written. Since we have no need for this file in
this case, leave this button unselected.
Since the other default options are satisfactory, select OK and then Update to the "Update
Project Statistics" dialog box to begin the classification.
The classification will be complete momentarily.
From the Window menu select Text Output, to bring the text window forward and make it
active, since it contains the classification results. The “TRAINING CLASS
PERFORMANCE (Resubstitution Method)” table tabulates how the pixels of each field
and class were classified. See example table below. There should be nearly 100% accuracy
on the training fields. If the Reference Accuracy is particularly low (say less than 50%) for
a class, then the training pixels for that class should be reexamined and new training pixels
selected.