int up, down; for (size_t j = result.cols - 1; j > 0; j--) { if (result.at<cv::Vec3b>(0, j) != cv::Vec3b(0, 0, 0)) { up = j; break; } } for (size_t j = result.cols - 1; j > 0; j--) { if (result.at<cv::Vec3b>(result.rows - 1, j) != cv::Vec3b(0, 0, 0)) { down = j; break; } } result = result(cv::Rect(0, 0, std::min(up, down) - 1, result.rows)); for (size_t i = 0; i < result.rows; i++) { if (result.at<cv::Vec3b>(i, img1.cols) != cv::Vec3b(0, 0, 0)) { up = i; break; } } for (size_t i = result.rows - 1; i > 0; i--) { if (result.at<cv::Vec3b>(i, img1.cols) != cv::Vec3b(0, 0, 0)) { down = i; break; } } cv::Mat img = result(cv::Rect(0, up + 1, result.cols, down - up - 1));解析

这段代码是对融合后的图像进行裁剪的过程。

首先，在变量up和down中分别记录融合后图像最上方和最下方不为全黑像素的列数。其中，up初始化为result.cols，down初始化为0。

接着，通过两个循环分别从融合后图像的最上方和最下方开始，遍历每一列像素，如果该列不是全黑像素，则将up或down更新为当前列数。

然后，通过ROI（Region of Interest）机制，将result变量中up和down之间的区域裁剪出来。其中，up和down分别加1和减1是为了避免裁剪出空白像素。

最后，将裁剪后的图像存储到img变量中。

相关问题

我想用c语言实现十字链表做矩阵加法

当然可以，以下是用 C 语言实现十字链表做矩阵加法的示例代码：

#include <stdio.h>
#include <stdlib.h>

struct MatrixNode {
    int row;
    int col;
    int value;
    struct MatrixNode* right;
    struct MatrixNode* down;
};

struct CrossMatrix {
    int rows;
    int cols;
    struct MatrixNode** row_heads;
    struct MatrixNode** col_heads;
    struct MatrixNode* head;
};

struct MatrixNode* create_node(int row, int col, int value) {
    struct MatrixNode* node = (struct MatrixNode*)malloc(sizeof(struct MatrixNode));
    node->row = row;
    node->col = col;
    node->value = value;
    node->right = NULL;
    node->down = NULL;
    return node;
}

struct CrossMatrix* create_cross_matrix(int rows, int cols) {
    struct CrossMatrix* matrix = (struct CrossMatrix*)malloc(sizeof(struct CrossMatrix));
    matrix->rows = rows;
    matrix->cols = cols;
    matrix->row_heads = (struct MatrixNode**)malloc(rows * sizeof(struct MatrixNode*));
    matrix->col_heads = (struct MatrixNode**)malloc(cols * sizeof(struct MatrixNode*));
    matrix->head = create_node(-1, -1, 0);
    matrix->head->right = matrix->col_heads[0] = create_node(-1, 0, 0);
    matrix->head->down = matrix->row_heads[0] = create_node(0, -1, 0);

    for (int i = 1; i < rows; i++) {
        matrix->row_heads[i] = create_node(i, -1, 0);
        matrix->row_heads[i - 1]->down = matrix->row_heads[i];
    }

    for (int i = 1; i < cols; i++) {
        matrix->col_heads[i] = create_node(-1, i, 0);
        matrix->col_heads[i - 1]->right = matrix->col_heads[i];
    }

    return matrix;
}

void insert(struct CrossMatrix* matrix, int row, int col, int value) {
    struct MatrixNode* node = create_node(row, col, value);
    struct MatrixNode* row_head = matrix->row_heads[row];
    struct MatrixNode* col_head = matrix->col_heads[col];

    struct MatrixNode* current_node = row_head;
    while (current_node->right && current_node->right->col < col) {
        current_node = current_node->right;
    }

    node->right = current_node->right;
    current_node->right = node;

    current_node = col_head;
    while (current_node->down && current_node->down->row < row) {
        current_node = current_node->down;
    }

    node->down = current_node->down;
    current_node->down = node;
}

struct CrossMatrix* add(struct CrossMatrix* matrix1, struct CrossMatrix* matrix2) {
    if (matrix1->rows != matrix2->rows || matrix1->cols != matrix2->cols) {
        printf("Matrices must have the same size\n");
        return NULL;
    }

    struct CrossMatrix* result = create_cross_matrix(matrix1->rows, matrix1->cols);

    for (int i = 0; i < matrix1->rows; i++) {
        struct MatrixNode* current_node1 = matrix1->row_heads[i]->right;
        struct MatrixNode* current_node2 = matrix2->row_heads[i]->right;

        while (current_node1 || current_node2) {
            if (current_node1 && (!current_node2 || current_node1->col < current_node2->col)) {
                insert(result, i, current_node1->col, current_node1->value);
                current_node1 = current_node1->right;
            }
            else if (current_node2 && (!current_node1 || current_node2->col < current_node1->col)) {
                insert(result, i, current_node2->col, current_node2->value);
                current_node2 = current_node2->right;
            }
            else {
                insert(result, i, current_node1->col, current_node1->value + current_node2->value);
                current_node1 = current_node1->right;
                current_node2 = current_node2->right;
            }
        }
    }

    return result;
}

void print_matrix(struct CrossMatrix* matrix) {
    for (int i = 0; i < matrix->rows; i++) {
        struct MatrixNode* current_node = matrix->row_heads[i]->right;

        for (int j = 0; j < matrix->cols; j++) {
            if (current_node && current_node->col == j) {
                printf("%d ", current_node->value);
                current_node = current_node->right;
            }
            else {
                printf("0 ");
            }
        }

        printf("\n");
    }
}

int main() {
    struct CrossMatrix* matrix1 = create_cross_matrix(3, 3);
    insert(matrix1, 0, 0, 1);
    insert(matrix1, 0, 1, 2);
    insert(matrix1, 1, 1, 3);
    insert(matrix1, 1, 2, 4);
    insert(matrix1, 2, 0, 5);
    insert(matrix1, 2, 2, 6);

    struct CrossMatrix* matrix2 = create_cross_matrix(3, 3);
    insert(matrix2, 0, 0, 7);
    insert(matrix2, 0, 1, 8);
    insert(matrix2, 1, 1, 9);
    insert(matrix2, 1, 2, 10);
    insert(matrix2, 2, 0, 11);
    insert(matrix2, 2, 2, 12);

    struct CrossMatrix* result = add(matrix1, matrix2);
    print_matrix(result);

    return 0;
}

这里使用了结构体实现节点和矩阵，定义了`create_node`和`create_cross_matrix`函数用于创建节点和十字链表形式的矩阵。还定义了`insert`和`add`函数用于插入节点和进行矩阵加法。最后，使用`print_matrix`函数打印出矩阵。

十字链表储存稀疏矩阵及稀疏矩阵相乘 C代码

下面是用十字链表储存稀疏矩阵和实现稀疏矩阵相乘的 C 代码示例：

#include <stdio.h>
#include <stdlib.h>

// 定义十字链表节点
typedef struct {
    int row;  // 行下标
    int col;  // 列下标
    int value;  // 元素值
    struct Node* right;  // 指向右边的节点
    struct Node* down;  // 指向下方的节点
} Node;

// 定义十字链表
typedef struct {
    int rows;  // 矩阵的行数
    int cols;  // 矩阵的列数
    Node* row_heads;  // 行头节点数组
    Node* col_heads;  // 列头节点数组
} CrossList;

// 创建稀疏矩阵对应的十字链表
CrossList* createCrossList(int rows, int cols) {
    CrossList* matrix = (CrossList*)malloc(sizeof(CrossList));
    matrix->rows = rows;
    matrix->cols = cols;
    matrix->row_heads = (Node*)malloc(rows * sizeof(Node));
    matrix->col_heads = (Node*)malloc(cols * sizeof(Node));
    
    // 初始化头节点数组
    for (int i = 0; i < rows; i++) {
        matrix->row_heads[i].right = NULL;
        matrix->row_heads[i].down = NULL;
    }
    
    for (int j = 0; j < cols; j++) {
        matrix->col_heads[j].right = NULL;
        matrix->col_heads[j].down = NULL;
    }
    
    return matrix;
}

// 向十字链表中插入元素
void insertElement(CrossList* matrix, int row, int col, int value) {
    Node* newNode = (Node*)malloc(sizeof(Node));
    newNode->row = row;
    newNode->col = col;
    newNode->value = value;
    
    // 插入新节点到行链表中
    Node* row_head = &(matrix->row_heads[row]);
    Node* cur = row_head;
    while (cur->right != NULL && cur->right->col < col) {
        cur = cur->right;
    }
    newNode->right = cur->right;
    cur->right = newNode;
    
    // 插入新节点到列链表中
    Node* col_head = &(matrix->col_heads[col]);
    cur = col_head;
    while (cur->down != NULL && cur->down->row < row) {
        cur = cur->down;
    }
    newNode->down = cur->down;
    cur->down = newNode;
}

// 打印稀疏矩阵的十字链表表示
void printCrossList(CrossList* matrix) {
    for (int i = 0; i < matrix->rows; i++) {
        Node* node = matrix->row_heads[i].right;
        for (int j = 0; j < matrix->cols; j++) {
            if (node != NULL && node->col == j) {
                printf("%d ", node->value);
                node = node->right;
            } else {
                printf("0 ");
            }
        }
        printf("\n");
    }
}

// 稀疏矩阵相乘
CrossList* multiplySparseMatrix(CrossList* matrix1, CrossList* matrix2) {
    if (matrix1->cols != matrix2->rows) {
        printf("Cannot multiply the matrices!");
        return NULL;
    }
    
    CrossList* result = createCrossList(matrix1->rows, matrix2->cols);
    
    for (int i = 0; i < matrix1->rows; i++) {
        Node* row_head = &(matrix1->row_heads[i]);
        Node* node1 = row_head->right;
        
        for (int j = 0; j < matrix2->cols; j++) {
            Node* col_head = &(matrix2->col_heads[j]);
            Node* node2 = col_head->down;
            
            int value = 0;
            while (node1 != NULL && node2 != NULL) {
                if (node1->col < node2->row) {
                    node1 = node1->right;
                } else if (node1->col > node2->row) {
                    node2 = node2->down;
                } else {
                    value += node1->value * node2->value;
                    node1 = node1->right;
                    node2 = node2->down;
                }
            }
            
            if (value != 0) {
                insertElement(result, i, j, value);
            }
        }
    }
    
    return result;
}

// 测试代码
int main() {
    CrossList* matrix1 = createCrossList(3, 3);
    insertElement(matrix1, 0, 0, 1);
    insertElement(matrix1, 0, 2, 2);
    insertElement(matrix1, 1, 1, 3);
    insertElement(matrix1, 2, 0, 4);
    insertElement(matrix1, 2, 2, 5);
    
    CrossList* matrix2 = createCrossList(3, 3);
    insertElement(matrix2, 0, 0, 1);
    insertElement(matrix2, 0, 1, 2);
    insertElement(matrix2, 1, 1, 3);
    insertElement(matrix2, 1, 2, 4);
    insertElement(matrix2, 2, 0, 5);
    
    CrossList* result = multiplySparseMatrix(matrix1, matrix2);
    printf("Result:\n");
    printCrossList(result);
    
    return 0;
}

这段代码实现了稀疏矩阵的十字链表存储以及稀疏矩阵的乘法操作。你可以根据需要修改矩阵的大小和元素值进行测试。