java图像处理sobel边缘检测

Question

I have a problem with java program, in which i'm using sobel operator for edge detection, but when I'm trying to use that funcion, console says:

Exception in thread "AWT-EventQueue-0" java.lang.ArrayIndexOutOfBoundsException: 262144 at sun.awt.image.ByteInterleavedRaster.getPixels(ByteInterleavedRaster.java:1015) at Obrazek.jButtonSobelActionPerformed(Obrazek.java:566)

And the code for that is:

 FileInputStream inFile = null; try { long beginTime = (new java.util.Date()).getTime(); int i, j; double Gx[][], Gy[][], G[][]; inFile = new FileInputStream("D://lenacsmall.bmp"); BufferedImage bi = ImageIO.read(inFile); int width = bi.getWidth(); int height = bi.getHeight(); int[] pixels = new int[width * height]; int[][] output = new int[width][height]; int[] raster = bi.getRaster().getPixels(0,0,width,height,pixels); int counter = 0; for(i = 0 ; i < width ; i++ ) { for(j = 0 ; j < height ; j++ ) { output[i][j] = pixels[counter]; counter = counter + 1; } } Gx = new double[width][height]; Gy = new double[width][height]; G = new double[width][height]; for (i=0; i<width; i++) { for (j=0; j<height; j++) { if (i==0 || i==width-1 || j==0 || j==height-1) Gx[i][j] = Gy[i][j] = G[i][j] = 0; else{ Gx[i][j] = output[i+1][j-1] + 2*output[i+1][j] + output[i+1][j+1] - output[i-1][j-1] - 2*output[i-1][j] - output[i-1][j+1]; Gy[i][j] = output[i-1][j+1] + 2*output[i][j+1] + output[i+1][j+1] - output[i-1][j-1] - 2*output[i][j-1] - output[i+1][j-1]; G[i][j] = Math.abs(Gx[i][j]) + Math.abs(Gy[i][j]); } } } counter = 0; for(int ii = 0 ; ii < width ; ii++ ) { for(int jj = 0 ; jj < height ; jj++ ) { pixels[counter] = (int) G[ii][jj]; counter = counter + 1; } } BufferedImage outImg = new BufferedImage(width,height,BufferedImage.TYPE_BYTE_GRAY); outImg.getRaster().setPixels(0,0,width,height,pixels); FileOutputStream outFile = null; try { outFile = new FileOutputStream("D://copyTop.bmp"); } catch (FileNotFoundException ex) { } try { ImageIO.write(outImg,"BMP",outFile); } catch (IOException ex) { } JFrame TheFrame = new JFrame("obrazek " + width + " " + height); JLabel TheLabel = new JLabel(new ImageIcon(outImg)); TheFrame.getContentPane().add(TheLabel); TheFrame.setSize(600, 600); TheFrame.addWindowListener(new WindowAdapter() { public void windowClosing(WindowEvent e) { System.exit(0); } }); TheFrame.setVisible(true); } catch (FileNotFoundException ex) { Logger.getLogger(Obrazek.class.getName()).log(Level.SEVERE, null, ex); } catch (IOException ex) { Logger.getLogger(Obrazek.class.getName()).log(Level.SEVERE, null, ex); } finally { try { inFile.close(); } catch (IOException ex) { Logger.getLogger(Obrazek.class.getName()).log(Level.SEVERE, null, ex); } } 

I'm really need some help. I hope someone will answer for that post, thank you.
Greetings :)

Answer 1

Try this, edge detection using sobel approach, I just did this yesterday.

`

static BufferedImage inputImg,outputImg;
static int[][] pixelMatrix=new int[3][3];

public static void main(String[] args) {
    try {

        inputImg=ImageIO.read(new File("your input image"));
        outputImg=new BufferedImage(inputImg.getWidth(),inputImg.getHeight(),TYPE_INT_RGB);

        for(int i=1;i<inputImg.getWidth()-1;i++){
            for(int j=1;j<inputImg.getHeight()-1;j++){
                pixelMatrix[0][0]=new Color(inputImg.getRGB(i-1,j-1)).getRed();
                pixelMatrix[0][1]=new Color(inputImg.getRGB(i-1,j)).getRed();
                pixelMatrix[0][2]=new Color(inputImg.getRGB(i-1,j+1)).getRed();
                pixelMatrix[1][0]=new Color(inputImg.getRGB(i,j-1)).getRed();
                pixelMatrix[1][2]=new Color(inputImg.getRGB(i,j+1)).getRed();
                pixelMatrix[2][0]=new Color(inputImg.getRGB(i+1,j-1)).getRed();
                pixelMatrix[2][1]=new Color(inputImg.getRGB(i+1,j)).getRed();
                pixelMatrix[2][2]=new Color(inputImg.getRGB(i+1,j+1)).getRed();

                int edge=(int) convolution(pixelMatrix);
                outputImg.setRGB(i,j,(edge<<16 | edge<<8 | edge));
            }
        }

        File outputfile = new File("your output image");
        ImageIO.write(outputImg,"jpg", outputfile);

    } catch (IOException ex) {System.err.println("Image width:height="+inputImg.getWidth()+":"+inputImg.getHeight());}
}
public static double convolution(int[][] pixelMatrix){

    int gy=(pixelMatrix[0][0]*-1)+(pixelMatrix[0][1]*-2)+(pixelMatrix[0][2]*-1)+(pixelMatrix[2][0])+(pixelMatrix[2][1]*2)+(pixelMatrix[2][2]*1);
    int gx=(pixelMatrix[0][0])+(pixelMatrix[0][2]*-1)+(pixelMatrix[1][0]*2)+(pixelMatrix[1][2]*-2)+(pixelMatrix[2][0])+(pixelMatrix[2][2]*-1);
    return Math.sqrt(Math.pow(gy,2)+Math.pow(gx,2));

}

`

Answer 2

In your for loops when you check

if (i==0 || i==width-1 || j==0 || j==height-1)

you should probably be checking for i >= width-2 rather than i==width-1.

For example, if width is 10 it falls into the statement if i == 9. you want to catch if i == 8 since you later check [i+1], which in your code would be out of the bounds of your image array, since the maximum you can have is 9 (width-1).

Obviously the same applies for j.