added gpu optical flow sample

samples/gpu/optical_flow.cpp

+#include <iostream>
+#include <fstream>
+
+#include "opencv2/core/core.hpp"
+#include "opencv2/highgui/highgui.hpp"
+#include "opencv2/gpu/gpu.hpp"
+
+using namespace std;
+using namespace cv;
+using namespace cv::gpu;
+
+inline bool isFlowCorrect(Point2f u)
+{
+    return !cvIsNaN(u.x) && !cvIsNaN(u.y) && fabs(u.x) < 1e9 && fabs(u.y) < 1e9;
+}
+
+static Vec3b computeColor(float fx, float fy)
+{
+    static bool first = true;
+
+    // relative lengths of color transitions:
+    // these are chosen based on perceptual similarity
+    // (e.g. one can distinguish more shades between red and yellow
+    //  than between yellow and green)
+    const int RY = 15;
+    const int YG = 6;
+    const int GC = 4;
+    const int CB = 11;
+    const int BM = 13;
+    const int MR = 6;
+    const int NCOLS = RY + YG + GC + CB + BM + MR;
+    static Vec3i colorWheel[NCOLS];
+
+    if (first)
+    {
+        int k = 0;
+
+        for (int i = 0; i < RY; ++i, ++k)
+            colorWheel[k] = Vec3i(255, 255 * i / RY, 0);
+
+        for (int i = 0; i < YG; ++i, ++k)
+            colorWheel[k] = Vec3i(255 - 255 * i / YG, 255, 0);
+
+        for (int i = 0; i < GC; ++i, ++k)
+            colorWheel[k] = Vec3i(0, 255, 255 * i / GC);
+
+        for (int i = 0; i < CB; ++i, ++k)
+            colorWheel[k] = Vec3i(0, 255 - 255 * i / CB, 255);
+
+        for (int i = 0; i < BM; ++i, ++k)
+            colorWheel[k] = Vec3i(255 * i / BM, 0, 255);
+
+        for (int i = 0; i < MR; ++i, ++k)
+            colorWheel[k] = Vec3i(255, 0, 255 - 255 * i / MR);
+
+        first = false;
+    }
+
+    const float rad = sqrt(fx * fx + fy * fy);
+    const float a = atan2(-fy, -fx) / (float) CV_PI;
+
+    const float fk = (a + 1.0f) / 2.0f * (NCOLS - 1);
+    const int k0 = static_cast<int>(fk);
+    const int k1 = (k0 + 1) % NCOLS;
+    const float f = fk - k0;
+
+    Vec3b pix;
+
+    for (int b = 0; b < 3; b++)
+    {
+        const float col0 = colorWheel[k0][b] / 255.0f;
+        const float col1 = colorWheel[k1][b] / 255.0f;
+
+        float col = (1 - f) * col0 + f * col1;
+
+        if (rad <= 1)
+            col = 1 - rad * (1 - col); // increase saturation with radius
+        else
+            col *= .75; // out of range
+
+        pix[2 - b] = static_cast<uchar>(255.0 * col);
+    }
+
+    return pix;
+}
+
+static void drawOpticalFlow(const Mat_<float>& flowx, const Mat_<float>& flowy, Mat& dst, float maxmotion = -1)
+{
+    dst.create(flowx.size(), CV_8UC3);
+    dst.setTo(Scalar::all(0));
+
+    // determine motion range:
+    float maxrad = maxmotion;
+
+    if (maxmotion <= 0)
+    {
+        maxrad = 1;
+        for (int y = 0; y < flowx.rows; ++y)
+        {
+            for (int x = 0; x < flowx.cols; ++x)
+            {
+                Point2f u(flowx(y, x), flowy(y, x));
+
+                if (!isFlowCorrect(u))
+                    continue;
+
+                maxrad = max(maxrad, sqrt(u.x * u.x + u.y * u.y));
+            }
+        }
+    }
+
+    for (int y = 0; y < flowx.rows; ++y)
+    {
+        for (int x = 0; x < flowx.cols; ++x)
+        {
+            Point2f u(flowx(y, x), flowy(y, x));
+
+            if (isFlowCorrect(u))
+                dst.at<Vec3b>(y, x) = computeColor(u.x / maxrad, u.y / maxrad);
+        }
+    }
+}
+
+static void showFlow(const char* name, const GpuMat& d_flowx, const GpuMat& d_flowy)
+{
+    Mat flowx(d_flowx);
+    Mat flowy(d_flowy);
+
+    Mat out;
+    drawOpticalFlow(flowx, flowy, out, 10);
+
+    imshow(name, out);
+}
+
+int main(int argc, const char* argv[])
+{
+    if (argc < 3)
+    {
+        cerr << "Usage : " << argv[0] << "<frame0> <frame1>" << endl;
+        return -1;
+    }
+
+    Mat frame0 = imread(argv[1], IMREAD_GRAYSCALE);
+    Mat frame1 = imread(argv[2], IMREAD_GRAYSCALE);
+
+    if (frame0.empty())
+    {
+        cerr << "Can't open image ["  << argv[1] << "]" << endl;
+        return -1;
+    }
+    if (frame1.empty())
+    {
+        cerr << "Can't open image ["  << argv[2] << "]" << endl;
+        return -1;
+    }
+
+    if (frame1.size() != frame0.size())
+    {
+        cerr << "Images should be of equal sizes" << endl;
+        return -1;
+    }
+
+    GpuMat d_frame0(frame0);
+    GpuMat d_frame1(frame1);
+
+    GpuMat d_flowx(frame0.size(), CV_32FC1);
+    GpuMat d_flowy(frame0.size(), CV_32FC1);
+
+    BroxOpticalFlow brox(0.197f, 50.0f, 0.8f, 10, 77, 10);
+    PyrLKOpticalFlow lk; lk.winSize = Size(7, 7);
+    FarnebackOpticalFlow farn;
+    OpticalFlowDual_TVL1_GPU tvl1;
+    FastOpticalFlowBM fastBM;
+
+    {
+        GpuMat d_frame0f;
+        GpuMat d_frame1f;
+
+        d_frame0.convertTo(d_frame0f, CV_32F, 1.0 / 255.0);
+        d_frame1.convertTo(d_frame1f, CV_32F, 1.0 / 255.0);
+
+        const int64 start = getTickCount();
+
+        brox(d_frame0f, d_frame1f, d_flowx, d_flowy);
+
+        const double timeSec = (getTickCount() - start) / getTickFrequency();
+        cout << "Brox : " << timeSec << " sec" << endl;
+
+        showFlow("Brox", d_flowx, d_flowy);
+    }
+
+    {
+        const int64 start = getTickCount();
+
+        lk.dense(d_frame0, d_frame1, d_flowx, d_flowy);
+
+        const double timeSec = (getTickCount() - start) / getTickFrequency();
+        cout << "LK : " << timeSec << " sec" << endl;
+
+        showFlow("LK", d_flowx, d_flowy);
+    }
+
+    {
+        const int64 start = getTickCount();
+
+        farn(d_frame0, d_frame1, d_flowx, d_flowy);
+
+        const double timeSec = (getTickCount() - start) / getTickFrequency();
+        cout << "Farn : " << timeSec << " sec" << endl;
+
+        showFlow("Farn", d_flowx, d_flowy);
+    }
+
+    {
+        const int64 start = getTickCount();
+
+        tvl1(d_frame0, d_frame1, d_flowx, d_flowy);
+
+        const double timeSec = (getTickCount() - start) / getTickFrequency();
+        cout << "TVL1 : " << timeSec << " sec" << endl;
+
+        showFlow("TVL1", d_flowx, d_flowy);
+    }
+
+    {
+        const int64 start = getTickCount();
+
+        GpuMat buf;
+        calcOpticalFlowBM(d_frame0, d_frame1, Size(7, 7), Size(1, 1), Size(21, 21), false, d_flowx, d_flowy, buf);
+
+        const double timeSec = (getTickCount() - start) / getTickFrequency();
+        cout << "BM : " << timeSec << " sec" << endl;
+
+        showFlow("BM", d_flowx, d_flowy);
+    }
+
+    {
+        const int64 start = getTickCount();
+
+        fastBM(d_frame0, d_frame1, d_flowx, d_flowy);
+
+        const double timeSec = (getTickCount() - start) / getTickFrequency();
+        cout << "Fast BM : " << timeSec << " sec" << endl;
+
+        showFlow("Fast BM", d_flowx, d_flowy);
+    }
+
+    imshow("Frame 0", frame0);
+    imshow("Frame 1", frame1);
+    waitKey();
+
+    return 0;
+}