I would like to display a image that is loaded in memory

1

Hi,
I would like to use TCPIP or UDP to send a JPEG file to the computer. I would like to grab the data in memory and display it. using client/server communications. Can I do that. Or do I have to write to the hard drive as a file then to imread to display the image.
I am very inexperienced with OpenCV. I would like to do this in C++.
Thank You,
Gary

2

Yes you can do that.

3

chatGPT gives sample code
Sender (server)

#include <opencv2/opencv.hpp>
#include <asio.hpp>          // single‑header Asio stand‑alone
using asio::ip::tcp;

int main() {
    cv::Mat img = cv::imread("frame.jpg", cv::IMREAD_COLOR);
    std::vector<uchar> buf;
    cv::imencode(".jpg", img, buf);

    asio::io_context io;
    tcp::acceptor acc(io, tcp::endpoint(tcp::v4(), 5000));
    tcp::socket sock(io);
    acc.accept(sock);

    // send size prefix (uint32_t, network byte order) then payload
    uint32_t n = htonl(static_cast<uint32_t>(buf.size()));
    asio::write(sock, asio::buffer(&n, sizeof n));
    asio::write(sock, asio::buffer(buf));
}

Receiver (client)

#include <opencv2/opencv.hpp>
#include <asio.hpp>
using asio::ip::tcp;

int main() {
    asio::io_context io;
    tcp::socket sock(io);
    sock.connect({asio::ip::make_address("127.0.0.1"), 5000});

    uint32_t n_net;          // read size prefix
    asio::read(sock, asio::buffer(&n_net, sizeof n_net));
    uint32_t n = ntohl(n_net);

    std::vector<uchar> buf(n);
    asio::read(sock, asio::buffer(buf));   // read JPEG bytes

    cv::Mat img = cv::imdecode(buf, cv::IMREAD_COLOR);
    cv::imshow("JPEG from RAM", img);
    cv::waitKey();
}
4

if the source is a file, that (decoding and encoding) can be reduced to simply reading the file into the buffer, without imread and imencode.