如何在图像中找到矩形的角坐标

Question

我在预处理原始图像后得到了这个图像。现在，我的问题是如何获得矩形的四个角坐标（最大）。对不起，如果这是noob问题。

更新：由于我使用OpenCV开发，最终使用this answer

Answer 1

一种简单的方法是：

1. 查找所有连接的组件
2. 计算每个组件的凸包
3. 选择凸包具有最大面积的组件
4. 简化凸包多边形
5. 简化多边形的顶点是您要查找的点

快速和肮脏的Mathematica解决方案：

(* find all connected components, calculate the convex hull for each component *)
convexHulls = ComponentMeasurements[ColorNegate[Binarize[src]], {"ConvexArea", "ConvexVertices"}];

(* pick the component where the convex hull has the largest area *)
vertices = SortBy[convexHulls[[All, 2]], First][[-1, 2]]

(* simplify the convex hull polygon, by iteratively removing the vertex with the lowest distance to the line through the vertex before and after it *)
distanceToNeighbors[vertices_] := MapThread[Abs[(#1 - #2).Cross[#1 - #3]/Norm[#1 - #3]]&, RotateLeft[vertices, #] & /@ {-1, 0, 1}]
removeVertexWithLowestDistance[vertices_] := With[{removeIndex = Ordering[distanceToNeighbors[vertices], 1]}, Drop[vertices, removeIndex]]
verticesSimplified = NestWhile[removeVertexWithLowestDistance, vertices, Min[distanceToNeighbors[#]] < 10&]

(* the vertices of the simplified polygon are the points you're looking for *)
Show[src, Graphics[
  {
   {EdgeForm[Red], Transparent, Polygon[verticesSimplified]},
   {Red, PointSize[Large], Point[verticesSimplified]}
   }]]