--- /dev/null
+Creating a 3D histogram {#tutorial_histo3D}
+================
+
+Goal
+----
+
+In this tutorial you will learn how to
+
+- Create your own callback keyboard function for viz window.
+- Show your 3D histogram in a viz window.
+
+Code
+----
+
+You can download the code from [here ](https://github.com/opencv/opencv/tree/master/samples/cpp/tutorial_code/viz/histo3D.cpp).
+@include samples/cpp/tutorial_code/viz/histo3D.cpp
+
+Explanation
+-----------
+
+Here is the general structure of the program:
+
+- You can give full path to an image in command line
+ @code{.cpp}
+ CommandLineParser parser(argc, argv, keys);
+
+ if (parser.has("help"))
+ {
+ parser.printMessage();
+ return 0;
+ }
+ String nomFic = parser.get<String>(0);
+ Mat img;
+ if (nomFic.length() != 0)
+ {
+ img = imread(nomFic, IMREAD_COLOR);
+ if (img.empty())
+ {
+ cout << "Image does not exist!";
+ return 0;
+ }
+ }
+ @endcode
+ or without path, a synthetic image is generated with pixel values are a gaussian distribution center(60+/-10,40+/-5,50+/-20) in first quadrant,
+ (160+/-20,10+/-5,50+/-10) in second quadrant, (90+/-10,100+/-20,50+/-20) in third quadrant, (100+/-10,10+/-5,150+/-40) in last quadrant.
+ @code{.cpp}
+ else
+ {
+ img = Mat(512,512,CV_8UC3);
+ parser.printMessage();
+ RNG r;
+ r.fill(img(Rect(0, 0, 256, 256)), RNG::NORMAL, Vec3b(60, 40, 50), Vec3b(10, 5, 20));
+ r.fill(img(Rect(256, 0, 256, 256)), RNG::NORMAL, Vec3b(160, 10, 50), Vec3b(20, 5, 10));
+ r.fill(img(Rect(0, 256, 256, 256)), RNG::NORMAL, Vec3b(90, 100, 50), Vec3b(10, 20, 20));
+ r.fill(img(Rect(256, 256, 256, 256)), RNG::NORMAL, Vec3b(100, 10, 150), Vec3b(10, 5, 40));
+ }
+ @endcode
+ Image tridimensional histogram is calculated using opencv calcHist and normalize between 0 and 100.
+ @code{.cpp}
+ float hRange[] = { 0, 256 };
+ const float* etendu[] = { hRange, hRange,hRange };
+ int hBins = 32;
+ int tailleHist[] = { hBins, hBins , hBins };
+ int canaux[] = { 2, 1,0 };
+ calcHist(&img, 1, canaux, Mat(), h.histogram, 3, tailleHist, etendu, true, false);
+ normalize(h.histogram, h.histogram, 100.0/(img.total()), 0, cv::NormTypes::NORM_MINMAX, -1, cv::Mat());
+ minMaxIdx(h.histogram,NULL,&h.maxH,NULL,NULL);
+ @endcode
+ channel are 2, 1 and 0 to synchronise color with Viz axis color in objetc viz::WCoordinateSystem.
+
+ A slidebar is inserted in image window. Init slidebar value is 90, it means that only histogram cell greater than 9/100000.0 (23 pixels for an 512X512 pixels) will be display.
+ @code{.cpp}
+ namedWindow("Image");
+ imshow("Image",img);
+ AddSlidebar("threshold","Image",0,100,h.seuil,&h.seuil, UpdateThreshold,&h);
+ waitKey(30);
+ @endcode
+ We are ready to open a viz window with a callback function to capture keyboard event in viz window. Using Viz::spinonce enable keyboard event to be capture in imshow window too.
+ @code{.cpp}
+ h.fen3D = new viz::Viz3d("3D Histogram");
+ h.nbWidget=0;
+ h.fen3D->registerKeyboardCallback(KeyboardViz3d,&h);
+ DrawHistogram3D(h);
+ while (h.code!=27)
+ {
+ h.fen3D->spinOnce(1);
+ if (h.status)
+ DrawHistogram3D(h);
+ if (h.code!=27)
+ h.code= waitKey(30);
+ }
+ @endcode
+ The function DrawHistogram3D processes histogram Mat to display it in a Viz window. Number of plan, row and column in three dimensional Mat ca be found using this code :
+ @code{.cpp}
+ int planSize = h.histogram.step1(0);
+ int cols = h.histogram.step1(1);
+ int rows = planSize / cols;
+ int plans = h.histogram.total() / planSize;
+ h.fen3D->removeAllWidgets();
+ h.nbWidget=0;
+ if (h.nbWidget==0)
+ h.fen3D->showWidget("Axis", viz::WCoordinateSystem(10));
+ @endcode
+ To get histogram value at a specific location we use at method with three arguments k, i and j where k is plane number, i row number and j column number.
+ @code{.cpp}
+ for (int k = 0; k < plans; k++)
+ {
+ for (int i = 0; i < rows; i++)
+ {
+ for (int j = 0; j < cols; j++)
+ {
+ double x = h.histogram.at<float>(k, i, j);
+ if (x >= h.threshold)
+ {
+ double r=std::max(x/h.maxH,0.1);
+ viz::WCube s(Point3d(k - r / 2, i - r / 2, j - r / 2), Point3d(k + r / 2, i + r / 2, j + r / 2), false, viz::Color(j / double(plans) * 255, i / double(rows) * 255, k / double(cols) * 255));
+ h.fen3D->showWidget(format("I3d%d", h.nbWidget++), s);
+ }
+ }
+ }
+ }
+ @endcode
+
+- Callback function
+ Principle are as mouse callback function. Key code pressed is in field code of class viz::KeyboardEvent.
+ @code{.cpp}
+ void KeyboardViz3d(const viz::KeyboardEvent &w, void *t)
+ {
+ Histo3DData *x=(Histo3DData *)t;
+ if (w.action)
+ cout << "you pressed "<< w.symbol<< " in viz window "<<x->fen3D->getWindowName()<<"\n";
+ x->code= w.code;
+ switch (w.code) {
+ case '/':
+ x->status=true;
+ x->threshold *= 0.9;
+ break;
+ case '*':
+ x->status = true;
+ x->threshold *= 1.1;
+ break;
+
+ }
+ if (x->status)
+ {
+ cout << x->threshold << "\n";
+ DrawHistogram3D(*x);
+ }
+ }
+ @endcode
+
+Results
+-------
+
+Here is the result of the program with no argument and threshold equal to 50.
+
+
--- /dev/null
+#include <opencv2/opencv.hpp>
+#include <iostream>
+
+using namespace std;
+using namespace cv;
+
+#ifdef HAVE_OPENCV_VIZ
+
+const String keys =
+"{Aide h usage ? help | | print this message }"
+"{@arg1 | | Full path to color imag (3 channels)}"
+;
+
+
+struct Histo3DData {
+ Mat histogram;
+ int seuil;
+ double threshold;
+ Ptr<viz::Viz3d> fen3D;
+ int nbWidget;
+ bool status;
+ double maxH;
+ int code;
+};
+
+void DrawHistogram3D(Histo3DData &);
+void AddSlidebar(String sliderName, String windowName, int sliderMin, int sliderMax, int valeurDefaut, int *sliderVal, void(*f)(int, void *), void *r);
+void UpdateThreshold(int , void * r);
+void KeyboardViz3d(const viz::KeyboardEvent &w, void *t);
+
+
+void DrawHistogram3D(Histo3DData &h)
+{
+ int planSize = h.histogram.step1(0);
+ int cols = h.histogram.step1(1);
+ int rows = planSize / cols;
+ int plans = h.histogram.total() / planSize;
+ h.fen3D->removeAllWidgets();
+ h.nbWidget=0;
+ if (h.nbWidget==0)
+ h.fen3D->showWidget("Axis", viz::WCoordinateSystem(10));
+ for (int k = 0; k < plans; k++)
+ {
+ for (int i = 0; i < rows; i++)
+ {
+ for (int j = 0; j < cols; j++)
+ {
+ double x = h.histogram.at<float>(k, i, j);
+ if (x >= h.threshold)
+ {
+ double r=std::max(x/h.maxH,0.1);
+ viz::WCube s(Point3d(k - r / 2, i - r / 2, j - r / 2), Point3d(k + r / 2, i + r / 2, j + r / 2), false, viz::Color(j / double(plans) * 255, i / double(rows) * 255, k / double(cols) * 255));
+ h.fen3D->showWidget(format("I3d%d", h.nbWidget++), s);
+ }
+ }
+ }
+ }
+ h.status = false;
+}
+
+void KeyboardViz3d(const viz::KeyboardEvent &w, void *t)
+{
+ Histo3DData *x=(Histo3DData *)t;
+ if (w.action)
+ cout << "you pressed "<< w.symbol<< " in viz window "<<x->fen3D->getWindowName()<<"\n";
+ x->code= w.code;
+ switch (w.code) {
+ case '/':
+ x->status=true;
+ x->threshold *= 0.9;
+ break;
+ case '*':
+ x->status = true;
+ x->threshold *= 1.1;
+ break;
+ }
+ if (x->status)
+ {
+ cout << x->threshold << "\n";
+ DrawHistogram3D(*x);
+ }
+}
+
+
+void AddSlidebar(String sliderName, String windowName, int sliderMin, int sliderMax, int defaultSlider, int *sliderVal, void(*f)(int, void *), void *r)
+{
+ createTrackbar(sliderName, windowName, sliderVal, 1, f, r);
+ setTrackbarMin(sliderName, windowName, sliderMin);
+ setTrackbarMax(sliderName, windowName, sliderMax);
+ setTrackbarPos(sliderName, windowName, defaultSlider);
+}
+
+
+void UpdateThreshold(int , void * r)
+{
+ Histo3DData *h = (Histo3DData *)r;
+ h->status=true;
+ h->threshold = h->seuil/1000000.0;
+ cout<<"Widget : "<<h->nbWidget<<","<< h->threshold<<"\n";
+}
+
+int main (int argc,char **argv)
+{
+ CommandLineParser parser(argc, argv, keys);
+
+ if (parser.has("help"))
+ {
+ parser.printMessage();
+ return 0;
+ }
+ String nomFic = parser.get<String>(0);
+ Mat img;
+ if (nomFic.length() != 0)
+ {
+ img = imread(nomFic, IMREAD_COLOR);
+ if (img.empty())
+ {
+ cout << "Image does not exist!";
+ return 0;
+ }
+ }
+ else
+ {
+ img = Mat(512,512,CV_8UC3);
+ parser.printMessage();
+ RNG r;
+ r.fill(img(Rect(0, 0, 256, 256)), RNG::NORMAL, Vec3b(60, 40, 50), Vec3b(10, 5, 20));
+ r.fill(img(Rect(256, 0, 256, 256)), RNG::NORMAL, Vec3b(160, 10, 50), Vec3b(20, 5, 10));
+ r.fill(img(Rect(0, 256, 256, 256)), RNG::NORMAL, Vec3b(90, 100, 50), Vec3b(10, 20, 20));
+ r.fill(img(Rect(256, 256, 256, 256)), RNG::NORMAL, Vec3b(100, 10, 150), Vec3b(10, 5, 40));
+ }
+ Histo3DData h;
+ h.status=true;
+ h.seuil=90;
+ h.threshold= h.seuil/1000000.0;
+ float hRange[] = { 0, 256 };
+ const float* etendu[] = { hRange, hRange,hRange };
+ int hBins = 32;
+ int histSize[] = { hBins, hBins , hBins };
+ int channel[] = { 2, 1,0 };
+ calcHist(&img, 1, channel, Mat(), h.histogram, 3, histSize, etendu, true, false);
+ normalize(h.histogram, h.histogram, 100.0/(img.total()), 0, NORM_MINMAX, -1, Mat());
+ minMaxIdx(h.histogram,NULL,&h.maxH,NULL,NULL);
+ namedWindow("Image");
+ imshow("Image",img);
+ AddSlidebar("threshold","Image",0,100,h.seuil,&h.seuil, UpdateThreshold,&h);
+ waitKey(30);
+
+ h.fen3D = new viz::Viz3d("3D Histogram");
+ h.nbWidget=0;
+ h.fen3D->registerKeyboardCallback(KeyboardViz3d,&h);
+ DrawHistogram3D(h);
+ while (h.code!=27)
+ {
+ h.fen3D->spinOnce(1);
+ if (h.status)
+ DrawHistogram3D(h);
+ if (h.code!=27)
+ h.code= waitKey(30);
+ }
+ return 0;
+}
+#else
+
+int main(int argc, char **argv)
+{
+cout << " you need VIZ module\n";
+return 0;
+}
+#endif
projects / platform / upstream / opencv.git / commitdiff
