不使用OPENCV库，用C++写一个图像渐进编码

以下是一个不使用OpenCV库的C++图像渐进编码示例：

#include <iostream>
#include <fstream>
#include <vector>
#include <cmath>

using namespace std;

// 将图像保存为二进制文件
void save_image(string filename, vector<vector<int>>& image) {
    ofstream file(filename, ios::out | ios::binary);
    int width = image[0].size();
    int height = image.size();
    file.write((char*)&width, sizeof(int));
    file.write((char*)&height, sizeof(int));
    for (int i = 0; i < height; i++) {
        file.write((char*)&image[i][0], sizeof(int) * width);
    }
    file.close();
}

// 从二进制文件中加载图像
void load_image(string filename, vector<vector<int>>& image) {
    ifstream file(filename, ios::in | ios::binary);
    int width, height;
    file.read((char*)&width, sizeof(int));
    file.read((char*)&height, sizeof(int));
    image.resize(height);
    for (int i = 0; i < height; i++) {
        image[i].resize(width);
        file.read((char*)&image[i][0], sizeof(int) * width);
    }
    file.close();
}

// 缩小图像
void downsample(vector<vector<int>>& image, vector<vector<int>>& downsampled) {
    int width = image[0].size();
    int height = image.size();
    int w = width / 2;
    int h = height / 2;
    downsampled.resize(h);
    for (int i = 0; i < h; i++) {
        downsampled[i].resize(w);
        for (int j = 0; j < w; j++) {
            downsampled[i][j] = (image[i * 2][j * 2] + image[i * 2][j * 2 + 1] + image[i * 2 + 1][j * 2] + image[i * 2 + 1][j * 2 + 1]) / 4;
        }
    }
}

// 放大图像
void upsample(vector<vector<int>>& image, vector<vector<int>>& upsampled) {
    int width = image[0].size();
    int height = image.size();
    int w = width * 2;
    int h = height * 2;
    upsampled.resize(h);
    for (int i = 0; i < h; i++) {
        upsampled[i].resize(w);
        for (int j = 0; j < w; j++) {
            int i1 = i / 2, j1 = j / 2;
            if (i % 2 == 0 && j % 2 == 0) {
                upsampled[i][j] = image[i1][j1];
            }
            else if (i % 2 == 0) {
                upsampled[i][j] = (image[i1][j1] + image[i1][j1 + 1]) / 2;
            }
            else if (j % 2 == 0) {
                upsampled[i][j] = (image[i1][j1] + image[i1 + 1][j1]) / 2;
            }
            else {
                upsampled[i][j] = (image[i1][j1] + image[i1][j1 + 1] + image[i1 + 1][j1] + image[i1 + 1][j1 + 1]) / 4;
            }
        }
    }
}

// 保存图像渐进编码结果
void save_result(string filename, vector<vector<vector<int>>>& result) {
    ofstream file(filename, ios::out | ios::binary);
    int level = result.size();
    file.write((char*)&level, sizeof(int));
    for (int i = 0; i < level; i++) {
        int width = result[i][0].size();
        int height = result[i].size();
        file.write((char*)&width, sizeof(int));
        file.write((char*)&height, sizeof(int));
        for (int j = 0; j < height; j++) {
            file.write((char*)&result[i][j][0], sizeof(int) * width);
        }
    }
    file.close();
}

// 加载图像渐进编码结果
void load_result(string filename, vector<vector<vector<int>>>& result) {
    ifstream file(filename, ios::in | ios::binary);
    int level;
    file.read((char*)&level, sizeof(int));
    result.resize(level);
    for (int i = 0; i < level; i++) {
        int width, height;
        file.read((char*)&width, sizeof(int));
        file.read((char*)&height, sizeof(int));
        result[i].resize(height);
        for (int j = 0; j < height; j++) {
            result[i][j].resize(width);
            file.read((char*)&result[i][j][0], sizeof(int) * width);
        }
    }
    file.close();
}

int main() {
    vector<vector<int>> image;
    load_image("test.bin", image); // 加载图像
    int level = 3; // 分成3层
    vector<vector<vector<int>>> result(level);
    result[0] = image;
    for (int i = 1; i < level; i++) {
        vector<vector<int>> downsampled;
        downsample(result[i - 1], downsampled); // 缩小图像
        result[i] = downsampled;
    }
    save_result("result.bin", result); // 保存渐进编码结果
    vector<vector<vector<int>>> decoded(level);
    decoded[level - 1] = result[level - 1];
    for (int i = level - 2; i >= 0; i--) {
        vector<vector<int>> upsampled;
        upsample(decoded[i + 1], upsampled); // 放大图像
        decoded[i] = upsampled;
    }
    save_image("decoded.bin", decoded[0]); // 保存解码结果
    return 0;
}

以上代码使用了vector容器和C++标准库中的fstream库来处理图像数据和文件输入输出。在encode()函数中，图像被分成level层，每一层都可以进行编码和传输；在decode()函数中，图像被重建成原始分辨率。在实际应用中，可以根据需要自定义编码和传输的方式。