C++中的PGM文件处理

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

// 读取PGM文件
std::vector<std::vector<int>> readPGM(const std::string& filename) {
    std::ifstream file(filename, std::ios::binary);
    std::vector<std::vector<int>> image;

    if (file.is_open()) {
        std::string format;
        int width, height, maxGrayValue;

        // 读取文件头信息
        file >> format >> width >> height >> maxGrayValue;

        // 读取像素灰度值
        image.resize(height, std::vector<int>(width));
        for (int i = 0; i < height; i++) {
            for (int j = 0; j < width; j++) {
                file >> image[i][j];
            }
        }

        file.close();
    }

    return image;
}

// 写入PGM文件
void writePGM(const std::string& filename, const std::vector<std::vector<int>>& image) {
    std::ofstream file(filename, std::ios::binary);

    if (file.is_open()) {
        int width = image[0].size();
        int height = image.size();
        int maxGrayValue = 255;

        // 写入文件头信息
        file << "P2" << std::endl;
        file << width << " " << height << std::endl;
        file << maxGrayValue << std::endl;

        // 写入像素灰度值
        for (int i = 0; i < height; i++) {
            for (int j = 0; j < width; j++) {
                file << image[i][j] << " ";
            }
            file << std::endl;
        }

        file.close();
    }
}

int main() {
    std::string inputFilename = "input.pgm";
    std::string outputFilename = "output.pgm";

    // 读取PGM文件
    std::vector<std::vector<int>> image = readPGM(inputFilename);

    // 对图像进行处理（例如，应用滤波器、调整亮度等）

    // 写入PGM文件
    writePGM(outputFilename, image);

    return 0;
}