C++ 读取bmp图片颜色信息

你可以使用C++的标准库和一些第三方库来读取bmp图片的颜色信息。

以下是使用标准库的代码示例：

#include <iostream>
#include <fstream>
#include <cstdint>

#pragma pack(push, 1)
struct BMPHeader {
    char id[2];
    uint32_t size;
    uint16_t reserved1;
    uint16_t reserved2;
    uint32_t offset;
    uint32_t dib_size;
    int32_t width;
    int32_t height;
    uint16_t planes;
    uint16_t bpp;
    uint32_t compression;
    uint32_t image_size;
    int32_t x_ppm;
    int32_t y_ppm;
    uint32_t color_used;
    uint32_t color_important;
};
#pragma pack(pop)

int main() {
    std::ifstream file("image.bmp", std::ios::binary); // 打开bmp文件
    if (!file.is_open()) {
        std::cerr << "Failed to open file\n";
        return 1;
    }

    BMPHeader header;
    file.read(reinterpret_cast<char*>(&header), sizeof(header)); // 读取bmp文件头
    if (header.id[0] != 'B' || header.id[1] != 'M') {
        std::cerr << "Invalid file format\n";
        return 1;
    }

    if (header.bpp != 24) { // 只处理24位bmp图像
        std::cerr << "Only 24-bit BMP images are supported\n";
        return 1;
    }

    const int32_t width = header.width;
    const int32_t height = std::abs(header.height);
    const uint32_t row_size = ((width * 3) + 3) / 4 * 4; // 每行字节数
    const uint32_t data_size = row_size * height; // 图像数据大小

    std::unique_ptr<uint8_t[]> data(new uint8_t[data_size]); // 分配内存用于存储图像数据
    file.read(reinterpret_cast<char*>(data.get()), data_size); // 读取图像数据

    // 从图像数据中提取颜色信息
    for (int32_t y = 0; y < height; ++y) {
        for (int32_t x = 0; x < width; ++x) {
            const uint8_t* pixel = &data[y * row_size + x * 3];
            const uint8_t red = pixel[2];
            const uint8_t green = pixel[1];
            const uint8_t blue = pixel[0];

            // 在这里处理颜色信息，比如输出每个像素点的RGB值
            std::cout << "Pixel (" << x << ", " << y << "): RGB("
                      << static_cast<int>(red) << ", "
                      << static_cast<int>(green) << ", "
                      << static_cast<int>(blue) << ")\n";
        }
    }

    return 0;
}

如果你想使用第三方库，可以考虑使用OpenCV库。以下是使用OpenCV读取bmp文件的代码示例：

#include <iostream>
#include <opencv2/opencv.hpp>

int main() {
    cv::Mat image = cv::imread("image.bmp", cv::IMREAD_COLOR); // 读取bmp文件
    if (image.empty()) {
        std::cerr << "Failed to open file\n";
        return 1;
    }

    // 提取颜色信息
    for (int32_t y = 0; y < image.rows; ++y) {
        for (int32_t x = 0; x < image.cols; ++x) {
            const cv::Vec3b& pixel = image.at<cv::Vec3b>(y, x);
            const uint8_t red = pixel[2];
            const uint8_t green = pixel[1];
            const uint8_t blue = pixel[0];

            // 在这里处理颜色信息，比如输出每个像素点的RGB值
            std::cout << "Pixel (" << x << ", " << y << "): RGB("
                      << static_cast<int>(red) << ", "
                      << static_cast<int>(green) << ", "
                      << static_cast<int>(blue) << ")\n";
        }
    }

    return 0;
}