Ignore Polarity

This can be specified to perform detection ignoring dark/light polarity of a trained model pattern.

Suppose you have two images as shown in Fig.1(i) and Fig.1(ii). The figures in Fig.1(i) and Fig.1(ii) have the same geometry because both are squares of the same size. However, Fig.1(i) has a dark square on a light background, while Fig.1(ii) has a light square on a dark background. The difference between these two concerns "which is light, workpiece (square) or background", i.e. the difference in dark/light polarity. If the patterns differ in dark/light polarity, the Locator Tool judges them different even when they are geometrically identical.

(i)
(ii)
Fig.1

Next, suppose that you teach the pattern in Fig.1(i) as the model pattern and then obtain images with the patterns shown in Fig.2. The image in Fig.2(i) has uneven brightness in the background, and the image in Fig.2(ii) has uneven brightness in the workpiece (square). The image in Fig.2(iii) has uneven brightness in both the background and the workpiece.

(i)
(ii)
(ii)
Fig.2

One thing to note is that "the human eye is quite insensible to dark/light polarity". What are shown in Fig.1 and Fig.2 are mere examples where the dark/light polarity is very easy to discern. In most actual images, "telling which is lighter and which is darker" requires a considerable amount of attention. If the tool fails to find a pattern, it might be necessary to check whether the "dark/light polarity is in the reverse direction".