# Polarity

By default, PatMax will only find matches where the trained pattern polarity and the run-time image pattern polarity are the same. You can specify that PatMax ignore the polarity of patterns in the run-time image. If you specify that PatMax ignore pattern polarity in the run-time image, you will increase the number of potential matches, which can increase image confusion. Also, ignoring pattern polarity reduces the search speed.

Note: You can change the value of this parameter at training time or run time with almost no execution time penalty, although the effect of changing the value can affect search speed.

The default for trained patterns specifies the darker side of a pattern boundary is negative and the lighter side of the boundary is positive. For example, see the following figure: