A single foreground region can surround a hole. Its region count and its boundary-loop count answer different questions.
Choose the counted entity
Binary boundary tracing can return exterior object boundaries and boundaries around holes. A list of such loops is not automatically a list of foreground components. The inclusion of holes and the selected connectivity need to be retained before a loop total is reported as an object total. Primary reference: MathWorks object and hole boundaries.
For an original counting sheet, create separate columns for foreground regions, exterior loops and hole loops. Identify whether the method includes holes. An empty interior can add a boundary without adding another foreground component, so the requested entity must be defined before results are compared.
Count a fictional ring
Imagine a three-by-three mask with foreground at all eight outside positions and background only at the center. Under a stated side-neighbor connectivity, the outside foreground is one connected ring. It has one exterior boundary and one boundary around its enclosed background hole.
A representation that includes both boundaries therefore has two loops but only one foreground region. This invented mask does not establish that one physical component or two objects were photographed. It only separates the entities counted from a chosen segmentation and boundary representation.
Review holes without changing the claim
Prepare an original drawing marking foreground membership and the enclosed background separately. Retain a holes-included flag beside any boundary collection. If later logic uses only exterior loops, preserve that selection explicitly rather than silently comparing its size with another method that retained holes.
This guide claims no HM object-counting capability and recommends no physical acceptance count. It asks whether the reporting unit is a foreground component or a boundary loop. That distinction should remain visible before image outputs are connected to a production or geometry question.
Customer Questions
How many foreground regions are in the fictional ring?
One under the stated connectivity.
How many loops include its hole boundary?
Two: one exterior and one hole loop.
Does a loop total always equal a region total?
No. Their counted entities differ.
Primary References
These references support the technical principles discussed in this guide. The worked examples and review questions are educational.
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