Convert between OpenCV Mat and Leptonica Pix

Question

I need to convert between OpenCV Mat image and Leptonica Pix image formats in C++. This is being used for binarization of 8bit gray images.

Answer 1

I know that i'm about 4 years late and nobody cares, but this task has frustrated me a lot 'cause leptonica's documentation is just awful.
The problem with @loot's answer is that it does not work with colored images, so here is my (maybe crude) modification of his pix8ToMat:

cv::Mat pixToMat(Pix *pix) {
    int width = pixGetWidth(pix);
    int height = pixGetHeight(pix);
    int depth = pixGetDepth(pix);

    cv::Mat mat(cv::Size(width, height), depth == 1 ? CV_8UC1 : CV_8UC3);

    for (uint32_t y = 0; y < height; ++y) {
        for (uint32_t x = 0; x < width; ++x) {
            if (depth == 1) {
                l_uint32 val;
                pixGetPixel(pix, x, y, &val);
                mat.at(cv::Point(x, y)) = static_cast(255 * val);
            } else {
                l_int32 r, g, b;
                pixGetRGBPixel(pix, x, y, &r, &g, &b);

                cv::Vec3b color(b, g, r);
                mat.at(cv::Point(x, y)) = color;
            }
        }
    }

    return mat;
}