1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
/**
* @file SobelDemo.java
* @brief Sample code using Sobel and/or Scharr OpenCV functions to make a simple Edge Detector
*/
import org.opencv.core.*;
import org.opencv.highgui.HighGui;
import org.opencv.imgcodecs.Imgcodecs;
import org.opencv.imgproc.Imgproc;
class SobelDemoRun {
public void run(String[] args) {
//! [declare_variables]
// First we declare the variables we are going to use
Mat src, src_gray = new Mat();
Mat grad = new Mat();
String window_name = "Sobel Demo - Simple Edge Detector";
int scale = 1;
int delta = 0;
int ddepth = CvType.CV_16S;
//! [declare_variables]
//! [load]
// As usual we load our source image (src)
// Check number of arguments
if (args.length == 0){
System.out.println("Not enough parameters!");
System.out.println("Program Arguments: [image_path]");
System.exit(-1);
}
// Load the image
src = Imgcodecs.imread(args[0]);
// Check if image is loaded fine
if( src.empty() ) {
System.out.println("Error opening image: " + args[0]);
System.exit(-1);
}
//! [load]
//! [reduce_noise]
// Remove noise by blurring with a Gaussian filter ( kernel size = 3 )
Imgproc.GaussianBlur( src, src, new Size(3, 3), 0, 0, Core.BORDER_DEFAULT );
//! [reduce_noise]
//! [convert_to_gray]
// Convert the image to grayscale
Imgproc.cvtColor( src, src_gray, Imgproc.COLOR_RGB2GRAY );
//! [convert_to_gray]
//! [sobel]
/// Generate grad_x and grad_y
Mat grad_x = new Mat(), grad_y = new Mat();
Mat abs_grad_x = new Mat(), abs_grad_y = new Mat();
/// Gradient X
//Imgproc.Scharr( src_gray, grad_x, ddepth, 1, 0, scale, delta, Core.BORDER_DEFAULT );
Imgproc.Sobel( src_gray, grad_x, ddepth, 1, 0, 3, scale, delta, Core.BORDER_DEFAULT );
/// Gradient Y
//Imgproc.Scharr( src_gray, grad_y, ddepth, 0, 1, scale, delta, Core.BORDER_DEFAULT );
Imgproc.Sobel( src_gray, grad_y, ddepth, 0, 1, 3, scale, delta, Core.BORDER_DEFAULT );
//! [sobel]
//![convert]
// converting back to CV_8U
Core.convertScaleAbs( grad_x, abs_grad_x );
Core.convertScaleAbs( grad_y, abs_grad_y );
//![convert]
//! [add_weighted]
/// Total Gradient (approximate)
Core.addWeighted( abs_grad_x, 0.5, abs_grad_y, 0.5, 0, grad );
//! [add_weighted]
//! [display]
HighGui.imshow( window_name, grad );
HighGui.waitKey(0);
//! [display]
System.exit(0);
}
}
public class SobelDemo {
public static void main(String[] args) {
// Load the native library.
System.loadLibrary(Core.NATIVE_LIBRARY_NAME);
new SobelDemoRun().run(args);
}
}