3 * @purpose Implementation of dilatometer related functions
8 #include "dilatometer.h"
12 static double test_left, test_right;
14 // Canny Edge algorithm variables
16 int lowThreshold = 30;
20 /** Buffers for storing image data. **/
21 static CvMat * g_srcRGB = NULL; // Source Image
22 static CvMat * g_srcGray = NULL; // Gray scale of source image
23 static CvMat * g_edges = NULL; // Detected Edges
25 /** Pointers for capturing image **/
26 static CvCapture * g_capture = NULL;
27 static IplImage * frame = NULL; // This is required as you can not use capture with CvMat in C
31 * Create a test image using left as left edge and right as right edge positions
33 void Dilatometer_TestImage()
36 g_srcRGB = cvCreateMat(480, 640, CV_8UC3);
38 for( int x = 0; x < 640; ++x)
40 for (int y = 0; y < 480; ++y)
43 for( int i = 0; i < 3; ++i)
45 s.val[i] = 210 + (rand() % 1000) * 1e-0 - (rand() % 1000) * 1e-0;
46 // Produce an exponential decay around left edge
48 s.val[i] *= exp( (x - test_left) / 25);
50 s.val[i] *= exp( (test_left - x) / 25);
51 // Produce an exponential decay around right edge
52 else if( x < test_right)
53 s.val[i] *= exp( (x - test_right) / 25);
55 s.val[i] *= exp( (test_right - x) / 25);
57 cvSet2D(g_srcRGB,y,x,s);
61 if (g_srcGray == NULL)
63 g_srcGray = cvCreateMat(g_srcRGB->rows,g_srcRGB->cols,CV_8UC1);
65 cvCvtColor(g_srcRGB,g_srcGray,CV_RGB2GRAY);
69 * Cleanup Dilatometer pointers
71 bool Dilatometer_Cleanup(int id)
73 if (g_capture != NULL)
74 cvReleaseCapture(&g_capture);
76 cvReleaseImageHeader(&frame);
77 //if (g_srcRGB != NULL)
78 // cvReleaseMat(&g_srcRGB); // Causing run time error in cvReleaseMat
79 if (g_srcGray != NULL)
80 cvReleaseMat(&g_srcGray);
82 cvReleaseMat(&g_edges);
87 * Get an image from the Dilatometer
89 static bool Dilatometer_GetImage()
92 // If more than one camera is connected, then input needs to be determined, however the camera ID may change after being unplugged
93 if( g_capture == NULL)
95 g_capture = cvCreateCameraCapture(0);
96 //If cvCreateCameraCapture returns NULL there is an error with the camera
97 if( g_capture == NULL)
104 // Get the frame and convert it to CvMat
105 frame = cvQueryFrame(g_capture);
107 g_srcRGB = cvGetMat(frame,&stub,0,0);
109 if( g_srcRGB == NULL)
112 // Convert the image to grayscale
113 if (g_srcGray == NULL)
115 g_srcGray = cvCreateMat(g_srcRGB->rows,g_srcRGB->cols,CV_8UC1);
118 cvCvtColor(g_srcRGB,g_srcGray,CV_RGB2GRAY);
123 void CannyThreshold()
125 if ( g_edges == NULL)
127 g_edges = cvCreateMat(g_srcGray->rows,g_srcGray->cols,CV_8UC1);
130 // Commented out lines are used during testing to show the image to screen, can also save the test images
131 //cvShowImage("display", g_srcGray);
134 // Reduce noise with a kernel blurxblur. Input the grayscale source image, output to edges. (0's mean it's determined from kernel sizes)
135 cvSmooth( g_srcGray, g_edges, CV_GAUSSIAN, blur, blur ,0 ,0 );
138 //cvSaveImage("test_blurred.jpg",g_edges,0);
140 //cvShowImage("display", g_edges);
143 // Find the edges in the image
144 cvCanny( g_edges, g_edges, lowThreshold, lowThreshold*ratio, kernel_size );
147 //cvSaveImage("test_edge.jpg",g_edges,0);
149 //cvShowImage("display", g_edges);
155 * Read the dilatometer image. The value changed will correspond to the new location of the edge.
156 * @param val - Will store the read value if successful
157 * @param samples - Number of rows to scan (increasing will slow down performance!)
158 * @returns true on successful read
160 bool Dilatometer_GetEdge( double * value, int samples)
164 // Get the image from the camera
165 result = Dilatometer_GetImage();
166 // If an error occured when capturing image then return
170 // Apply the Canny Edge theorem to the image
173 int width = g_edges->cols;
174 int height = g_edges->rows;
176 // If the number of samples is greater than the image height, sample every row
177 if( samples > height)
183 int num_edges = 0; // Number of edges. if each sample location has an edge, then num_edges = samples
185 for (int i=0; i<samples; i++)
187 // Determine the position in the rows to find the edges.
188 // This will give you a number of evenly spaced samples
189 sample_height = ceil(height * (i + 1) / samples) -1;
191 // 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).
195 for ( int col = 0; col < width; col++)
197 // Count the number of points
198 // Get the threshold of the pixel at the current location
199 CvScalar value = cvGet2D(g_edges, sample_height, col);
200 if( value.val[0]> THRES)
202 edge_location += col;
208 average += ( edge_location / num );
213 average /= num_edges;
217 result = true; //Successfully found an edge
224 * Read the dilatometer image. The value changed will correspond to the new location of the edge.
225 * @param val - Will store the read value if successful
226 * @returns true on successful read
228 bool Dilatometer_Read(int id, double * value)
230 bool result = Dilatometer_GetEdge(value, SAMPLES);
235 * Initialise the dilatometer
237 bool Dilatometer_Init(const char * name, int id)
239 // Make an initial reading (will allocate memory the first time only).
241 Dilatometer_GetEdge(&val, 1);
245 // Overlays a line over the given edge position
246 void Draw_Edge(double edge)
250 for( int i = 0; i < g_srcGray->rows; i++)
252 cvSet2D(g_edges,i,edge,value);
254 cvShowImage("display", g_edges);
256 //cvSaveImage("test_edge_avg.jpg",g_edges,0);
260 static void Dilatometer_GetImageTest( )
262 //Generates Test image
263 //Dilatometer_TestImage();
266 g_srcGray = cvLoadImageM ("testimage4.jpg",CV_LOAD_IMAGE_GRAYSCALE );
270 * For testing purposes
272 /*int main(int argc, char ** argv)
274 //cvNamedWindow( "display", CV_WINDOW_AUTOSIZE );// Create a window for display.
275 //gettimeofday(&start, NULL);
280 cvNamedWindow( "display", CV_WINDOW_AUTOSIZE);
284 Dilatometer_GetEdge(&edge,20000);
285 //For testing purposes, overlay the given average line over the image
288 cvDestroyWindow("display");
290 Dilatometer_Cleanup();