This is about edge detection using java

[moon123]

constructing a edge detector using sobel kernels with a discrete convolution algorithm. The result should give a vertical edge image, a horizontal edge image and a gradient image.

Sobel kernels :


[-1 0 1
hx = -2 0 2 and
-1 0 1]


[-1 -2 -1
hy = 0 0 0
1 2 1]


gradeint magnitude and direction:

g = (g2x + g2y) 1/2 and (theta) = tan-1 (gy/gx)

The following code can be used :

[code=java]
import java.io.*;

public class JPEG1{


public static void main (String args[]) {
/* Check that the user has provided the right number of arguments */
if (args.length != 2) {
System.out.prin tln("Usage: java JPEGCopy <source JPEG file> " +
"<target JPEG file>");
System.exit(1);
}

/* Create an empty image. We will read an image from a file into
this object */
JPEGImage imageOne = new JPEGImage();

/* Try to open the file. This may cause an exception if the name
given is not a valid JPEG file so we need to catch the exceptions */
try {
imageOne.read(a rgs[0]);
} catch (Exception e) {
/* An exception has been thrown. This is usually because the file
either does not exist, or is not a JPEG image */
System.out.prin tln("Error reading file " + args[0]);
System.out.prin tln(e.getMessag e());
System.exit(1);
}

/* Make a new image the same size as the one that was read in */
JPEGImage imageTwo = new JPEGImage(image One.getWidth(),
imageOne.getHei ght());

/* Copy the pixel information from image that was read in to the
new image */
for (int x = 0; x < imageOne.getWid th(); x++) {
for (int y = 0; y < imageOne.getHei ght(); y++) {
/* Get the values from imageOne */
int red = imageOne.getRed (x,y);
int green = imageOne.getGre en(x,y);
int blue = imageOne.getBlu e(x,y);
/* Put these values into imageTwo */
imageTwo.setRGB (x, y, red, green, blue);
}
}

/* Write the new image out to a file. Again exceptions might occur */
try {
imageTwo.write( args[1]);
} catch (Exception e) {
System.out.prin tln("Error writing file " + args[1]);
System.out.prin tln(e.getMessag e());
System.exit(1);
}

}
}[/code]