C++车牌号识别代码

        Mat gray;
    cvtColor(src, gray, COLOR_BGR2GRAY);
    Mat thresh;
    threshold(gray, thresh, 0, 255, THRESH_BINARY_INV | THRESH_OTSU);

    //使用形态学开操作去除一些小轮廓
    Mat kernel = getStructuringElement(MORPH_RECT, Size(3, 3));
    Mat open;
    morphologyEx(thresh, open, MORPH_OPEN, kernel);

以上每句代码是什么意思

1. cvtColor(src, gray, COLOR_BGR2GRAY)：将src图像转换为灰度图像，保存到gray中。
2. threshold(gray, thresh, 0, 255, THRESH_BINARY_INV | THRESH_OTSU)：对灰度图像gray进行二值化处理，将结果保存到thresh中。
3. Mat kernel = getStructuringElement(MORPH_RECT, Size(3, 3))：创建一个3x3的矩形结构元素，保存到kernel中。
4. morphologyEx(thresh, open, MORPH_OPEN, kernel)：对thresh图像进行形态学开操作，使用kernel结构元素，将结果保存到open中。

该回答引用ChatGPT-3.5

这段代码使用OpenCV库实现了车牌号的识别，主要步骤如下：

• 将彩色图像转换为灰度图像

  cvtColor(src, gray, COLOR_BGR2GRAY);
  

  该函数将原始彩色图像 src 转换为灰度图像 gray，使用的颜色转换模式为 COLOR_BGR2GRAY。

• 对灰度图像进行二值化处理

  threshold(gray, thresh, 0, 255, THRESH_BINARY_INV | THRESH_OTSU);
  

  该函数将灰度图像 gray 进行二值化处理，并将结果保存到 thresh 中。函数参数中的 0 表示阈值，这里使用了 Otsu 自适应阈值方法，使得图像的前景和背景能够更好地分离，同时也采用了反向二值化操作 THRESH_BINARY_INV。

• 使用形态学开操作去除一些小轮廓

  Mat kernel = getStructuringElement(MORPH_RECT, Size(3, 3));
  Mat open;
  morphologyEx(thresh, open, MORPH_OPEN, kernel);
  

  这里使用了形态学开操作 MORPH_OPEN，去除一些小的轮廓噪声，使得车牌号的轮廓更加清晰。 getStructuringElement 函数创建一个大小为 3x3 的矩形形态学元素，morphologyEx 函数将二值化后的图像 thresh 进行开操作，使用的形态学元素为 kernel，开操作的结果保存在 open 中。

• 你可以看下这个问题的回答https://ask.csdn.net/questions/28115
• 我还给你找了一篇非常好的博客，你可以看看是否有帮助，链接：车牌识别C++的代码错误记录
• 除此之外, 这篇博客: C++ 红黑树中的 实现代码 部分也许能够解决你的问题, 你可以仔细阅读以下内容或跳转源博客中阅读:
  

• (没封装版)

  #pragma once
  #include <iostream>
  using namespace std;
  
  
  //red-black tree
  enum Color
  {
  	RED,
  	BLACK
  };
  template<class K,class V>
  struct RBTreeNode
  {
  	RBTreeNode<K, V>* _left;
  	RBTreeNode<K, V>* _right;
  	RBTreeNode<K, V>* _parent;
  
  	pair<K, V> _kv;
  	Color _col;
  	
  	RBTreeNode(const pair<K,V>& kv)
  		:_left(nullptr)
  		, _right(nullptr)
  		, _parent(nullptr)
  		, _kv(kv)
  		, _col(RED)
  	{}
  };
  template<class K,class V>
  struct _TreeIterator
  {
  	typedef RBTreeNode<K, V> Node;
  	Node* _node;
  	_TreeIterator(Node* node)
  		:_node(node)
  	{}
  	//operator*();
  	//operator++();
  	//operator--();
  };
  template<class K,class V>
  class RBTree
  {
  	typedef RBTreeNode<K, V> Node;
  public:
  	RBTree()
  		:_root(nullptr)
  	{}
  	void _Destory(Node* root)
  	{
  		if (root == nullptr)
  		{
  			return;
  		}
  		_Destory(root->_left);
  		_Destory(root->_right);
  		delete root;
  	}
  	~RBTree()
  	{
  		_Destory(_root);
  		_root = nullptr;
  	}
  	Node* Find(const K& key)
  	{
  		Node* cur = _root;
  		while (cur)
  		{
  			if (cur->_kv.first > key)
  			{
  				cur = cur->_left;
  			}
  			else if (cur->_kv.first < key)
  			{
  				cur = cur->_right;
  			}
  			else
  			{
  				return cur;
  			}
  		}
  		return nullptr;
  	}
  	pair<Node*, bool> Insert(const pair<K, V>& kv)
  	{
  		if (_root == nullptr)
  		{
  			_root = new Node(kv);
  			_root->_col = BLACK;
  			return make_pair(_root, true);
  		} 
  		Node* parent = nullptr;
  		Node* cur = _root;
  		while (cur)
  		{
  			if (cur->_kv.first < kv.first)
  			{
  				parent = cur;
  				cur = cur->_right;
  			}
  			else if (cur->_kv.first > kv.first)
  			{
  				parent = cur;
  				cur = cur->_left;
  			}
  			else
  			{
  				return make_pair(cur, false);
  			}
  		}
  		Node* newnode = new Node(kv);
  		newnode->_col = RED;
  		if (parent->_kv.first < kv.first)
  		{
  			parent->_right = newnode;
  			newnode->_parent = parent;
  		}
  		else
  		{
  			parent->_left = newnode;
  			newnode->_parent = parent;
  		}
  		//插入的结点是黑色还是红色？
  		//插入红色结点，可能破坏规则3，但是影响不大
  		//插入黑色结点，一定破坏规则4，并且会影响其他路径，影响面很大
  		cur = newnode;
  		//如果父亲存在，且颜色为红色就需要处理
  		while (parent && parent->_col == RED)
  		{
  			//关键看叔叔
  			Node* grandfather = parent->_parent;
  			if (parent == grandfather->_left)
  			{
  				Node* uncle = grandfather->_right;
  				if (uncle && uncle->_col == RED)
  				{
  					//情况1：uncle 存在且为红
  					//把parent和uncle变黑，grandfather变红
  					parent->_col = uncle->_col = BLACK;
  					grandfather->_col = RED;
  
  					//继续往上处理
  					cur = grandfather;
  					parent = cur->_parent;
  
  				}
  				else
  				{
  					//情况2+3
  					//uncle不存在或uncle存在且为黑
  					if (cur == parent->_left)
  					{
  						//情况2：需要右单旋
  						RotateR(grandfather);
  						grandfather->_col = RED;
  						parent->_col = BLACK;
  					}
  					else
  					{
  						//情况3：左右双旋
  						RotateL(parent);
  						RotateR(grandfather);
  						cur->_col = BLACK;
  						grandfather->_col = RED;
  
  					}
  					break;
  				}
  			}
  			else//parent == grandfather->right
  			{
  				Node* uncle = grandfather->_left;
  				if (uncle && uncle->_col == RED)
  				{
  					//情况一
  					uncle->_col = parent->_col = BLACK;
  					grandfather->_col = RED;
  					cur = grandfather;
  					parent = cur->_parent;
  
  				}
  				else
  				{
  					//情况2+情况3
  					if (cur == parent->_right)
  					{
  						RotateL(grandfather);
  						parent->_col = BLACK;
  						grandfather->_col = RED;
  					}
  					else // cur == parent->_left
  					{
  						RotateR(parent);
  						RotateL(grandfather);
  						cur->_col = BLACK;
  						grandfather->_col = RED;
  					}
  					//插入结束
  					break;
  				}
  			}
  
  		}
  		_root->_col = BLACK;
  		return make_pair(newnode, true);
  		
  	}
  	void RotateR(Node* parent)
  	{
  		Node* subl = parent->_left;
  		Node* sublr = subl->_right;
  		parent->_left = sublr;
  		if (sublr)
  		{
  			sublr->_parent = parent;
  		}
  
  		subl->_right = parent;
  		Node* parentparent = parent->_parent;
  		parent->_parent = subl;
  		if (parent == _root)
  		{
  			//是一个独立的树
  			_root = subl;
  			_root->_parent = nullptr;
  		}
  		else
  		{
  			//只是子树,parent还有parent
  			if (parentparent->_left == parent)
  			{
  				parentparent->_left = subl;
  			}
  			else
  			{
  				parentparent->_right = subl;
  			}
  			subl->_parent = parentparent;
  		}
  		
  	}
  	void RotateL(Node* parent)
  	{
  		Node* subr = parent->_right;
  		Node* subrl = subr->_left;
  
  		parent->_right = subrl;
  		if (subrl)
  		{
  			subrl->_parent = parent;
  		}
  		Node* parentparent = parent->_parent;
  		subr->_left = parent;
  		parent->_parent = subr;
  
  		if (parent == _root)
  		{
  			//是独立的树
  			_root = subr;
  			_root->_parent = nullptr;
  		}
  		else
  		{
  			//是子树
  			if (parentparent->_left == parent)
  				parentparent->_left = subr;
  
  			else
  				parentparent->_right = subr;
  
  			subr->_parent = parentparent;
  
  		}
  		
  	}
  	bool  _CheckBalance(Node* root, int blacknum, int count)
  	{
  		if (root == nullptr)
  		{
  			if (count != blacknum)
  			{
  				cout << "黑色结点数目不相等" << endl;
  				return false;
  			}
  			return true;
  		}
  		if (root->_col == RED && root->_parent->_col == RED)
  		{
  			cout << "存在连续红色" << endl;
  			return false;
  		}
  		if (root->_col == BLACK)
  		{
  			count++;
  		}
  		return _CheckBalance(root->_left,blacknum,count)
  			&& _CheckBalance(root->_right,blacknum,count);
  	}
  	bool CheckBalance()
  	{
  		if (_root == nullptr)
  		{
  			return true;
  		}
  		if (_root->_col == RED)
  		{
  			cout << "root is red" << endl;
  			return false;
  		}
  		//找最左路径做参考值
  		int blacknum = 0;
  		Node* left = _root;
  		while (left)
  		{
  			if (left->_col == BLACK)
  			{
  				blacknum++;
  			}
  			left = left->_left;
  		}
  		int count = 0;
  		return _CheckBalance(_root, blacknum, count);
  	}
  	void _Inorder(Node* root)
  	{
  		if (root == nullptr)
  		{
  			return;
  		}
  		_Inorder(root->_left);
  		cout << root->_kv.first <<"->"<<root->_kv.second<< endl ;
  		_Inorder(root->_right);
  	}
  	void Inorder()
  	{
  		_Inorder(_root);
  		
  	}
  
  private:
  	Node* _root;
  };