--- /dev/null
+/**
+ * @file dilatometer.c
+ * @purpose Implementation of dilatometer related functions
+ */
+
+#include "cv.h"
+#include "highgui_c.h"
+#include "dilatometer.h"
+#include <math.h>
+
+// test positions
+static double test_left, test_right;
+
+// Canny Edge algorithm variables
+int blur = 5;
+int lowThreshold = 30;
+int ratio = 3;
+int kernel_size = 3;
+
+/** Buffers for storing image data. **/
+static CvMat * g_srcRGB = NULL; // Source Image
+static CvMat * g_srcGray = NULL; // Gray scale of source image
+static CvMat * g_edges = NULL; // Detected Edges
+static CvMat * g_data = NULL;
+
+/** Pointers for capturing image **/
+static CvCapture * g_capture = NULL;
+static IplImage * frame = NULL; // This is required as you can not use capture with CvMat in C
+
+
+/**
+ * Create a test image using left as left edge and right as right edge positions
+ */
+void Dilatometer_TestImage()
+{
+
+ g_srcRGB = cvCreateMat(480, 640, CV_8UC3);
+
+ for( int x = 0; x < 640; ++x)
+ {
+ for (int y = 0; y < 480; ++y)
+ {
+ CvScalar s;
+ for( int i = 0; i < 3; ++i)
+ {
+ s.val[i] = 210 + (rand() % 1000) * 1e-0 - (rand() % 1000) * 1e-0;
+ // Produce an exponential decay around left edge
+ if( x < test_left)
+ s.val[i] *= exp( (x - test_left) / 25);
+ else if( x < 320)
+ s.val[i] *= exp( (test_left - x) / 25);
+ // Produce an exponential decay around right edge
+ else if( x < test_right)
+ s.val[i] *= exp( (x - test_right) / 25);
+ else
+ s.val[i] *= exp( (test_right - x) / 25);
+ }
+ cvSet2D(g_srcRGB,y,x,s);
+ }
+
+ }
+ if (g_data == NULL)
+ {
+ g_data = cvCreateMat(g_srcRGB->rows,g_srcRGB->cols,CV_8UC1);
+ }
+ cvCvtColor(g_srcRGB,g_data,CV_RGB2GRAY);
+}
+
+/**
+ * Cleanup Dilatometer pointers
+ */
+void Dilatometer_Cleanup()
+{
+ if (g_data != NULL)
+ cvReleaseMat(&g_data);
+ if (g_capture != NULL)
+ cvReleaseCapture(&g_capture);
+ if (g_srcRGB != NULL)
+ cvReleaseMat(&g_srcRGB);
+ if (g_srcGray != NULL)
+ cvReleaseMat(&g_srcGray);
+ if (g_edges != NULL)
+ cvReleaseMat(&g_edges);
+ if (frame != NULL)
+ cvReleaseImageHeader(&frame);
+}
+
+/**
+ * Get an image from the Dilatometer
+ */
+static bool Dilatometer_GetImage()
+{
+ bool result = true;
+ // If more than one camera is connected, then input needs to be determined, however the camera ID may change after being unplugged
+ g_capture = cvCreateCameraCapture(0);
+
+ //If cvCreateCameraCapture returns NULL there is an error with the camera
+ if( g_capture == NULL)
+ result = false;
+
+ // Get the frame and convert it to CvMat
+ frame = cvQueryFrame(g_capture);
+ CvMat stub;
+ g_srcRGB = cvGetMat(frame,&stub,0,0);
+
+ if( g_srcRGB == NULL)
+ result = false;
+
+ return result;
+}
+
+void CannyThreshold()
+{
+
+ if (g_data == NULL)
+ {
+ g_data = cvCreateMat(g_srcGray->rows,g_srcGray->cols,CV_8UC1);
+ }
+
+ if ( g_edges == NULL)
+ {
+ g_edges = cvCreateMat(g_srcGray->rows,g_srcGray->cols,CV_8UC1);
+ }
+
+ // Commented out lines are used during testing to show the image to screen, can also save the test images
+ //cvShowImage("display", g_srcGray);
+ //cvWaitKey(0);
+
+ // Reduce noise with a kernel blurxblur. Input the grayscale source image, output to edges. (0's mean it's determined from kernel sizes)
+ cvSmooth( g_srcGray, g_edges, CV_GAUSSIAN, blur, blur ,0 ,0 );
+
+ //Save the image
+ //cvSaveImage("test_blurred.jpg",g_edges,0);
+
+ //cvShowImage("display", g_edges);
+ //cvWaitKey(0);
+
+ // Find the edges in the image
+ cvCanny( g_edges, g_edges, lowThreshold, lowThreshold*ratio, kernel_size );
+
+ //Save the image
+ //cvSaveImage("test_edge.jpg",g_edges,0);
+
+ //cvShowImage("display", g_edges);
+ //cvWaitKey(0);
+
+}
+
+ /**
+ * Read the dilatometer image. The value changed will correspond to the new location of the edge.
+ * @param val - Will store the read value if successful
+ * @param samples - Number of rows to scan (increasing will slow down performance!)
+ * @returns true on successful read
+ */
+bool Dilatometer_GetEdge( double * value, int samples)
+{
+ bool result = false;
+ double average = 0;
+ // Get the image from the camera
+ result = Dilatometer_GetImage();
+ // If an error occured when capturing image then return
+ if (!result)
+ return result;
+
+ // Apply the Canny Edge theorem to the image
+ CannyThreshold();
+
+ int width = g_edges->cols;
+ int height = g_edges->rows;
+
+ // If the number of samples is greater than the image height, sample every row
+ if( samples > height)
+ {
+ samples = height;
+ }
+
+ int sample_height;
+ int num_edges = 0; // Number of edges. if each sample location has an edge, then num_edges = samples
+
+ for (int i=0; i<samples; i++)
+ {
+ // Determine the position in the rows to find the edges.
+ // This will give you a number of evenly spaced samples
+ sample_height = ceil(height * (i + 1) / samples) -1;
+
+ // Need to go through each pixel of a row and find all the locations of a line. If there is more than one pixel, average it. note this only works if the canny edge algorithm returns lines about the actual line (no outliers).
+
+ int edge_location=0;
+ int num=0;
+ for ( int col = 0; col < width; col++)
+ {
+ // Count the number of points
+ // Get the threshold of the pixel at the current location
+ CvScalar value = cvGet2D(g_edges, sample_height, col);
+ if( value.val[0]> THRES)
+ {
+ edge_location += col;
+ num++;
+ }
+ }
+ if( num > 0)
+ {
+ average += ( edge_location / num );
+ num_edges++;
+ }
+ }
+ if (num_edges > 0)
+ average /= num_edges;
+
+ if( average > 0)
+ {
+ result = true; //Successfully found an edge
+ *value = average;
+ }
+ return result;
+}
+
+ /**
+ * Read the dilatometer image. The value changed will correspond to the new location of the edge.
+ * @param val - Will store the read value if successful
+ * @returns true on successful read
+ */
+bool Dilatometer_Read( double * value)
+{
+ bool result = Dilatometer_GetEdge(value, SAMPLES);
+ return result;
+}
+
+/**
+ * Initialise the dilatometer
+ */
+void Dilatometer_Init()
+{
+ // Make an initial reading (will allocate memory the first time only).
+ double val;
+ Dilatometer_GetEdge(&val, 1);
+}
+
+// Overlays a line over the given edge position
+void Draw_Edge(double edge)
+{
+ CvScalar value;
+ value.val[0]=244;
+ for( int i = 0; i < g_srcGray->rows; i++)
+ {
+ cvSet2D(g_edges,i,edge,value);
+ }
+ cvShowImage("display", g_edges);
+ cvWaitKey(0);
+ cvSaveImage("test_edge_avg.jpg",g_edges,0);
+}
+
+/*// Test algorithm
+static void Dilatometer_GetImageTest( )
+{
+ //Generates Test image
+ //Dilatometer_TestImage();
+
+ //Load Test image
+ g_srcGray = cvLoadImageM ("testimage4.jpg",CV_LOAD_IMAGE_GRAYSCALE );
+}*/
+
+/**
+ * For testing purposes
+ */
+/*int main(int argc, char ** argv)
+{
+ //cvNamedWindow( "display", CV_WINDOW_AUTOSIZE );// Create a window for display.
+ //gettimeofday(&start, NULL);
+ test_left = 100;
+ test_right = 500;
+ Dilatometer_Init();
+
+ cvNamedWindow( "display", CV_WINDOW_AUTOSIZE);
+// cvShowImage("display", g_data);
+// cvWaitKey(0);
+ double width;
+
+ double edge;
+ Dilatometer_Read(&edge,20000);
+ //For testing purposes, overlay the given average line over the image
+ Draw_Edge(edge);
+
+ cvDestroyWindow("display");
+
+}*/
+
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