The program ships with some predefined targets but you can define their own. There are three classes of target: 1) ideal isolated targets, 2) ideal infinite extent targets, and 3) natural targets. Each of these targets has different capabilities and different restrictions.
An ideal target is an abstraction. For example a cross target is defined with perfectly sharp and straight edges although the target will never look like this in a real image. An isolated target is one where the target sits alone with background surrounding it. An infinite extent target is one where the target is matched to only a part of object and the target will not be surrounded by background (i.e. target’s edge(s) extend to the edge of the template image). Natural targets are pieces of imagery as they would look in a real image - they do not have a uniform background but are not infinite in extent.
Templates are defined by a bitmap image file (bmp, tiff, jpeg, etc.) but for the ideal targets a loss-less format like bmp or tiff is preferred. Ideal targets are defined as white targets on a black background. They can be either sense in the photographs (i.e. white targets or black targets).
The different target types are described below and the Importing Target Templates section has an image of the examples described.