Basic Library

Update 27 Desember 2012

Basic,

  • Mat Image;  //Membuat  variabel image
  • namedWindow( “Display window”, CV_WINDOW_AUTOSIZE ); //Membuat image
  • imshow( “Display window”, image ); //Memperlihatkan image di console
  • waitKey(0); //delay user key press
  • image = imread(“robot.jpg”,1); // Read the file roi.create(1024,768,CV_8UC3); // create image
    roi2.create(image.size(),CV_8UC3); // copy size image

Save & Load Image dari file,

  • image = imread(argv[1], CV_LOAD_IMAGE_COLOR); //Membaca image
    • CV_LOAD_IMAGE_UNCHANGED (<0) loads the image as is (including the alpha channel if present).
    • CV_LOAD_IMAGE_GRAYSCALE ( 0) loads the image as an intensity one.
    • CV_LOAD_IMAGE_COLOR (>0) loads the image in the RGB format
  • imwrite( “../../images/Gray_Image.jpg”, gray_image ); //Menyimpan image

Basic Drawing,

  • Point(titik)
    Point pt;
    pt.x = 10;
    pt.y = 8;
    atau,
    Point pt =  Point(10, 8);
  • Scalar( a, b, c );
  • Mat src = Mat::zeros( 400, 400, CV_8UC3 ); //membuat blank image
  • rectangle( src,Point(0, 0),Point( 0, 0),Scalar(0, 255, 255 ),1 ); //kotak
  • circle(img, Point(100,100), 20, Scalar(0,255,0), 1); //lingkaran
  • line(img, Point(100,100), Point(200,200), Scalar(0,255,0), 1); //garis
  • ellipse( img,Point(100, 100 ),Size( 200, 200 ),angle,0,360,Scalar( 255, 0, 0 ),thickness,lineType );
  • putText (image2,”My comment”,Point(200,400), 1,2, Scalar(255,255,0),1,8); //tulisan

Filtering,

  • cvtColor( image, gray_image, CV_RGB2GRAY );
  • erode( src, erosion_dst, element ); //erosion
  • dilate( src, dilation_dst, element ); //dilation
  • blur(InputArray src, OutputArray dst, Size ksize, Point anchor=Point(-1,-1), int borderType=BORDER_DEFAULT ) //smoothing
  • GaussianBlur( src, src, Size(3,3), 0, 0, BORDER_DEFAULT );
  • morphologyEx( src, dst, operation, element ); //New filtering
    • operation,
      • Opening
      • Closing
      • Morphological gradient
      • Top Hat
      • Black Hat
    • Element
      • int morph_elem = 0;
      • int morph_size = 0;
      • int morph_operator = 0;
      • int const max_operator = 4;
      • int const max_elem = 2;
      • int const max_kernel_size = 21;
        • Mat element = getStructuringElement( morph_elem, Size( 2*morph_size + 1, 2*morph_size+1 ), Point( morph_size, morph_size ) );
  • Sobel
    int scale = 1;
    int delta = 0;
    int ddepth = CV_16S;/// Generate grad_x and grad_y
    Mat grad_x, grad_y;
    Mat abs_grad_x, abs_grad_y;/// Gradient X
    //Scharr( src_gray, grad_x, ddepth, 1, 0, scale, delta, BORDER_DEFAULT );
    Sobel( src_gray, grad_x, ddepth, 1, 0, 3, scale, delta, BORDER_DEFAULT );
    convertScaleAbs( grad_x, abs_grad_x );/// Gradient Y
    //Scharr( src_gray, grad_y, ddepth, 0, 1, scale, delta, BORDER_DEFAULT );
    Sobel( src_gray, grad_y, ddepth, 0, 1, 3, scale, delta, BORDER_DEFAULT );
    convertScaleAbs( grad_y, abs_grad_y );

    /// Total Gradient (approximate)
    addWeighted( abs_grad_x, 0.5, abs_grad_y, 0.5, 0, grad );
    imshow( window_name, grad );

    Gambar 1. sobel
  • Laplace
    int kernel_size = 3;
    int scale = 1
    ;int delta = 0;
    int ddepth = CV_16S;/// Apply Laplace function
    Mat abs_dst;Laplacian( src_gray, dst, ddepth, kernel_size, scale, delta, BORDER_DEFAULT );
    convertScaleAbs( dst, abs_dst ); //convert to CV_8U image

    Gambar 2. laplace
  • Canny
    int edgeThresh = 1;
    int lowThreshold;
    int const max_lowThreshold = 100;
    int ratio = 3;
    int kernel_size = 3;/// Reduce noise with a kernel 3×3
    blur( src_gray, detected_edges, Size(3,3) );/// Canny detector
    Canny( detected_edges, detected_edges, lowThreshold, lowThreshold*ratio, kernel_size );/// Using Canny’s output as a mask, we display our result
    dst = Scalar::all(0);

    imshow( window_name, dst );

    Gambar 3. Canny

Accessing Pixel,

  • Scalar intensity = img.at(y, x); //Grayscale
    • img.at(y, x) = 128; //Mengubah scale intensity
  • Scalar intensity = img.at(Point(x, y)); //RGB
    • Vec3b intensity = img.at(y, x); //uchar
      uchar blue = intensity.val[0];
      uchar green = intensity.val[1];
      uchar red = intensity.val[2];
    • Vec3f intensity = img.at(y, x); //float
      float blue = intensity.val[0];
      float green = intensity.val[1];
      float red = intensity.val[2];
  • int dataimg = image.at(y,x); //Ambil data pixel

Scaling/Resize image,

  • pyrUp( tmp, dst, Size( tmp.cols*2, tmp.rows*2 ); //Zoom Out
  • pyrDown( tmp, dst, Size( tmp.cols/2, tmp.rows/2 ); //Zoom In

Memory Managemant, <Penting!!!>

  • Mat img = imread(“image.jpg”);
    Mat img1 = img.clone(); //clone image
  • Mat img2
    img.copyTo(img2); //copy image
  • src.convertTo(dst, CV_32F);  //convert image
    • CV_8U, CV_8S, CV_16U, CV_16S, CV_32S, CV_32F, CV_64F.

Converter, <Penting!!!>

  • ///converting IplImage to cv::Mat  
 Mat image=cvarrToMat(img);  
  • ///Converting Mat to IplImage
    (you have cv::Mat old)
 IplImage copy = old;
 IplImage* new_image = &copy;

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