A set of constraints can be specified, limiting the blobs that are found by the tool (result validation). The constraints apply to each blob, and all must be satisfied for a blob to be considered qualified.

Circularity - Minimum and maximum circularity limits to accept a blob

Note: A smooth factor of 2 or 3 will normally lead to a better circularity estimate

Axis ratio - Minimum and maximum limit values for axis ratio *see note below

Axis ratio is length / width of bounding box.

Angle - Minimum and maximum limit values for angle

Length of bounding box - Minimum and maximum length limits for bounding box *see note below

Width of bounding box - Minimum and maximum width limits for bounding box  *see note below

Ignore blobs touching ROI border - blobs only partly inside the ROI can be removed. WARNING: if the ROI contains holes, this will give you incorrect results.

* Note on axes and bounding box

This tool does not calculate a true (minimum) bounding box. The blob axes (and hence the "bounding box") are calculated using different order moments of the surrounding polygon and an eigenvalue analysis of a matrix containing the moments of inertia.

The major/minor axes are sound results in some respects, but using the true minimum bounding box (possible in Blob4) gives more understandable results.