OpenCV and Unsharp Masking Like Adobe Photoshop

Question

I am trying to implement unsharp masking like it\'s done in Adobe Photoshop. I gathered a lot of information on the interent but I\'m not sure if I\'m missing something. Here\'s

Answer 1

Here's the code what I have done. I am using this code to implement Unsharp Mask and it is working well for me. Hope it is useful for you.

void USM(cv::Mat &O, int d, int amp, int threshold)
{
    cv::Mat GB;
    cv::Mat O_GB;
    cv::subtract(O, GB, O_GB);

    cv::Mat invGB = cv::Scalar(255) - GB;

    cv::add(O, invGB, invGB);

    invGB = cv::Scalar(255) - invGB;

    for (int i = 0; i < O.rows; i++)
    {
        for (int j = 0; j < O.cols; j++)
        {
            unsigned char o_rgb = O.at(i, j);
            unsigned char d_rgb = O_GB.at(i, j);
            unsigned char inv_rgb = invGB.at(i, j);

            int newVal = o_rgb;
            if (d_rgb >= threshold)
            {
                newVal = o_rgb + (d_rgb - inv_rgb) * amp;
                if (newVal < 0)      newVal = 0;
                if (newVal > 255)    newVal = 255;
            }

            O.at(i, j) = unsigned char(newVal);
        }
    }

}