What is simple border points)

The more conceptual the problem is, the more confusing it is. However, you may think it is too simple. The less information you have on the Internet.

Let's get a new one from kaiwii ......

In Graphics, there is a concept called simple border points ).

Before explaining this concept, I would like to talk about the application scenarios of this concept.

For example, domain operations in graphics and thinning.

Next, I want to talk about what is connected component.

For a two-value graph, its 4-connected and 8-connected may have different connected components. In fact, this is very understandable.

For a 4-node connection, a point A is adjacent to B as long as its east, south, west, and North is a bit B.

For eight connections, we will discuss the joining of the two points in more than four directions, including the southeast and northwest directions.

If we understand under what circumstances, the two points are adjacent, then the connected variables can be understood as such a vertex set, and a vertex can certainly pass through its adjacent contacts, or through its adjacent contacts ...... Recursively locate the vertices in any vertex set.

You can understand the concept of connected variables! Congratulations! We can move on to the subject: What is simple border points)

First concept:

If a vertex P in S has only one connected component adjacent to s in its neighbor, P is a simple boundary point of S.

You can understand or not understand this concept. I mainly point out two keywords: Only one, connected component.

Before starting the example, we will talk about the connected components. There are two points that you must pay attention:

1. When you divide a connection domain, you must regard point P as thing-less.

2. Check whether the image is 4-connected or 8-connected when two points are connected.

Next, let me talk about my understanding in specific examples.

Analysis:

In the case of 4 connections,

The point P in Figure 1 is only connected to the connected component 1, so P is a simple boundary point.

The point P in Figure 2 is connected to the connected components 1 and 2, so P is not a simple boundary point.

The P point in Figure 3 is not connected to any connected component, so P is not a simple boundary point.

In the case of 8 connections,

The point P in Figure 1 is connected to the connected components 1 and 2, so P is not a simple boundary point.

The point P in Figure 2 is connected to the connected components 1 and 2, so P is not a simple boundary point.

The point P in Figure 3 is only connected to the connected component 1, so P is a simple boundary point.

Finally, in the case of eight connections, let's look at another example for your consideration:

Kaiwii! Thank you!