After getting the OpenCV using mac port I ran into trouble linking projects using the OpenCV functionalities. Using linux, it is as easy as setting the “-lcv” linker flag. Using OSX, I was only successfull when the library paths are returned by the pkg-config utility. You can run the command without the back ticks, and copy its outputs in your makefile, or just copy the command with the back ticks inside your makefile:
pkg-config --libs --cflags opencv
After getting the OpenCV using mac port I ran into trouble linking projects using the OpenCV functionalities. Using linux, it is as easy as setting the “-lcv” linker flag. Using OSX, I was only successfull when the library paths are returned by the pkg-config utility. You can run the command without the back ticks, and copy its outputs in your makefile, or just copy the command with the back ticks inside your makefile:
pkg-config --libs --cflags opencv
This short piece of code below captures a frame from a web cam and shows it in a window. Some simple transformations can be applied.
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#include <stdio.h> #include <highgui.h> int main(void) { //we assume, that there is only one camera CvCapture* capture= cvCaptureFromCAM(-1); IplImage* img; int loop; while(loop++<100) { cvGrabFrame(capture); // capture a frame img=cvRetrieveFrame(capture,1); // retrieve the captured frame // get the properties of the image int width = img->width; int height = img->height; int nchannels = img->nChannels; int step = img->widthStep; // setup the pointer to access image data uchar *data = ( uchar* )img->imageData; int i, j, value; int Rin, Gin, Bin; int Rout, Gout, Bout; for( i = 0 ; i < height ; i++ ) { for( j = 0 ; j < width ; j++ ) { Rin = data[i*step + j*nchannels + 0]; Gin = data[i*step + j*nchannels + 1]; Bin = data[i*step + j*nchannels + 2]; //------ begin image maniupulation ------ //one-to-one mapping //Rout=Rin;Gout=Gin;Bout=Bin; //grayscale conversion //Rout = Gout = Bout = ( Rin + Gin + Bin ) / 3; //some black and white thresholding Rout = Gout = Bout = ( Rin + Gin + Bin ) > 3*255/2 ? 255: 0; //------ end image maniupulation ------ data[i*step + j*nchannels + 0] = Rout; data[i*step + j*nchannels + 1] = Gout; data[i*step + j*nchannels + 2] = Bout; } } cvShowImage("video output", img); cvWaitKey(20); } cvReleaseCapture(&capture); return 0; } |
The code is simply compiled with:
gcc -Wall highgui_test.c -o highgui_test -lcv -I /usr/include/opencv/ -lhighgui
