Added cvWatershedSegmentation to the project.

Author: karlphillip

README.md

@@ -31,3 +31,7 @@ QtFPSvsTIMEanimation
 --------------
 A Qt implementation of FPS-based and Time-based animation techniques, as explained by Steven Lambert:
 http://blog.sklambert.com/using-time-based-animation-implement/
+
+cvWatershedSegmentation
+--------------
+A simple watershed segmentation example using distance transform to segment beans.

cvWatershedSegmentation/beans.png

@@ -0,0 +1,109 @@
+/* A simple Watershed segmentation example, as described at:
+ * http://stackoverflow.com/a/25851951/176769
+ */
+#include <iostream>
+#include <vector>
+
+#include <opencv2/highgui/highgui.hpp>
+#include <opencv2/imgproc/imgproc.hpp>
+
+int main()
+{
+    cv::Mat img = cv::imread("beans.png");
+    if (img.empty())
+    {
+        std::cout << "!!! Failed to open image" << std::endl;
+        return -1;
+    }
+
+    /* Pre-processing */
+
+    // Convert input image to grayscale
+    cv::Mat img_gray;
+    cv::cvtColor(img, img_gray, cv::COLOR_BGR2GRAY);
+
+    // Threshold the image and retrieve its binary representation
+    cv::Mat img_bin;
+    cv::threshold(img_gray, img_bin, 128, 255, cv::THRESH_OTSU | cv::THRESH_BINARY_INV);
+    cv::imwrite("img_bin.png", img_bin);
+
+    // Remove small objects (noises)
+    cv::Mat three_by_three_element(5, 5, CV_8U, cv::Scalar(1));
+    cv::morphologyEx(img_bin, img_bin, cv::MORPH_OPEN, three_by_three_element);
+    cv::imwrite("img_bin_morphoEx.png", img_bin);
+
+    /* Processing */
+
+    // Get the borders of the objects (beans)
+    cv::Mat dilation, erosion;
+    cv::dilate(img_bin, dilation, cv::Mat(), cv::Point(-1,-1), 3);
+    cv::erode(dilation, erosion, cv::Mat());
+    cv::Mat border(img_bin.size(), CV_8U, cv::Scalar(0));
+    border = dilation - erosion;
+    cv::imwrite("border.png", border);
+
+    // Get the distance transform and normalize the result to [0,255]
+    cv::Mat dt;
+    cv::distanceTransform(img_bin, dt, cv::DIST_L2, 5);
+    cv::normalize(dt, dt, 0, 255, cv::NORM_MINMAX);
+
+    // Threshold it to isolate the peaks
+    cv::threshold(dt, dt, 135, 255, cv::THRESH_BINARY);
+    cv::imwrite("dt_thres.png", dt);
+
+    // Use connectedComponents() to isolate the objects
+    dt.convertTo(dt, CV_8U);
+    cv::Mat lbl(dt.size(), CV_32S);
+    int ncc = cv::connectedComponents(dt, lbl, 4);
+    //std::cout << "Number of Connected Components: " << ncc << std::endl;
+
+    // Create a gray color spectrum to paint the peaks
+    std::vector<unsigned char> colors(ncc);
+    colors[0] = 0; // for background
+    for(int label = 1; label < ncc; ++label)
+        colors[label] = 255/ncc*label;
+
+    // Paint every peak (bean candidate) with a shade of gray
+    for (int x = 0; x < dt.rows; x++) {
+        for (int y = 0; y < dt.cols; y++) {
+            int label = lbl.at<int>(x, y);
+            dt.at<unsigned char>(x, y) = colors[label];
+         }
+    }
+    cv::imwrite("conn_comp.png", dt);
+
+    // Create the marker image for watershed
+    cv::Mat markers = cv::Mat::zeros(dt.size(), CV_8U);
+    markers = dt + border;
+    cv::imwrite("markers.png", markers);
+
+    markers.convertTo(markers, CV_32SC1);
+    cv::watershed(img, markers);
+
+    markers.convertTo(markers, CV_8U);
+    markers = 255 - markers; // cv::bitwise_not()
+    cv::imwrite("watershed.png", markers);
+
+    // Create a green mask with the sillhuete of the detected objects
+    cv::Mat green_mask = cv::Mat::zeros(markers.size(), CV_8UC3);
+    for (int i = 0; i < markers.rows; i++)
+    {
+        for (int j = 0; j < markers.cols; j++)
+        {
+            // Draw the marker's silhuete (white) as green in the mask
+            if (markers.at<unsigned char>(i,j) == 255)
+                green_mask.at<cv::Vec3b>(i,j) = cv::Vec3b(0, 255, 0);
+        }
+    }
+
+    cv::dilate(green_mask, green_mask, cv::Mat());
+    cv::imshow(std::string("result"), green_mask);
+
+    cv::Mat result = img + green_mask;
+    cv::imshow(std::string("result"), result);
+    cv::imwrite("result.png", result);
+
+    cv::waitKey(0);
+
+    return 0;
+}

cvWatershedSegmentation/main.cpp

@@ -0,0 +1,14 @@
+## OpenCV settings for Windows and OpenCV 3.0 Alpha
+win32 {
+        message("* Using settings for Windows.")
+    INCLUDEPATH += "C:\\opencv\\build\\include" \
+                   "C:\\opencv\\build\\include\\opencv" \
+                   "C:\\opencv\\build\\include\\opencv2"
+
+    LIBS += -L"C:\\opencv\\build\\x86\\vc12\\lib" \
+        -lopencv_world300d
+}
+
+SOURCES += \
+    main.cpp
+