103 lines
3.1 KiB
Markdown
103 lines
3.1 KiB
Markdown
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---
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author: Sanchayan Maity
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title: Face detection with OpenCV
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tags: face detection, opencv
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---
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Below is the code for face detection in OpenCV.
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<pre><code>
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#include "opencv/cv.h"
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#include "opencv/cxcore.h"
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#include "opencv/highgui.h"
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#include "stdio.h"
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int main()
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{
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IplImage* frame = NULL;
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const char* cascade_path = "C:\\OpenCV\\opencv\\data\\haarcascades\\haarcascade_frontalface_alt2.xml";
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CvHaarClassifierCascade* hc = NULL;
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CvMemStorage* storage = cvCreateMemStorage(0);
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CvSize minSize = cvSize(100, 100);
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CvSize maxSize = cvSize(640, 480);
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CvSeq* faces = NULL;
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CvCapture* input_camera = NULL;
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int key = 0;
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int loopCounter = 0;
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hc = (CvHaarClassifierCascade*)cvLoad(cascade_path, NULL, NULL, NULL);
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if (hc == NULL)
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{
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printf("\nLoading of classifier failed\n");
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return -1;
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}
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input_camera = cvCaptureFromCAM(-1);
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if (input_camera == NULL)
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{
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printf("\nCould not open camera\n");
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return -1;
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}
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//Grabs and returns a frame from camera
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frame = cvQueryFrame(input_camera);
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if (frame == NULL)
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{
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printf("\nCould not capture frame\n");
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return -1;
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}
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cvNamedWindow("Capturing Image ...", 0);
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cvResizeWindow("Capturing Image ...",
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(int) cvGetCaptureProperty(input_camera, CV_CAP_PROP_FRAME_HEIGHT),
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(int) cvGetCaptureProperty(input_camera, CV_CAP_PROP_FRAME_WIDTH));
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while(frame != NULL)
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{
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faces = cvHaarDetectObjects(frame, hc, storage, 1.2, 3, CV_HAAR_DO_CANNY_PRUNING, minSize, maxSize);
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for (loopCounter = 0; loopCounter < (faces ? faces->total : 0); loopCounter++)
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{
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CvRect *r = (CvRect*)cvGetSeqElem(faces, loopCounter);
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CvPoint pt1 = { r->x, r->y };
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CvPoint pt2 = { r->x + r->width, r->y + r->height };
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cvRectangle(frame, pt1, pt2, CV_RGB(0, 255, 0), 3, 4, 0);
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}
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//Shows a frame
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cvShowImage("Capturing Image ...", frame);
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// Checks if ESC is pressed and gives a delay
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// so that the frame can be displayed properly
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key = cvWaitKey(1);
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if (key == 27) // ESC key
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{
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break;
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}
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//Grabs and returns the next frame
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frame = cvQueryFrame(input_camera);
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}
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//cvReleaseImage( &frame );
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cvReleaseCapture(&input_camera);
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cvReleaseMemStorage( &storage );
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cvReleaseHaarClassifierCascade( &hc );
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//Destroy the window
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cvDestroyWindow("Capturing Image ...");
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return 0;
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}</code></pre>
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<p style='text-align: justify;'>I have tested the above code on a NVidia Tegra2 with Toradex Colibri T20 module and also on my laptop. Works, but there is a bug it seems. The program crashes if I enable the cvReleaseImage() line. Not an OpenCV expert, will have to really study the functions properly before playing around I guess. Will update this as soon as i found out.</p>
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<p style='text-align: justify;'>I have not explained the OpenCV installation procedure for windows as it is already documented on the OpenCV website.</p>
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<p style='text-align: justify;'>For using with Beagleboard you can refer to a previous article of mine</p>
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[http://coherentmusings.wordpress.com/2012/06/24/getting-started-with-opencv-on-beagleboard-xm/](http://coherentmusings.wordpress.com/2012/06/24/getting-started-with-opencv-on-beagleboard-xm/).
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<p style='text-align: justify;'>You can also use OpenCV with embedded Linux if you use Buildroot or OpenEmbedded for building your image.</p>
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