Sobel 运算符不适用于矩形图像
Sobel operator doesn't work with rectangle images
我尝试在 Java 中实现 Sobel 运算符,但结果只是混合了一些像素。
int i, j;
FileInputStream inFile = new FileInputStream(args[0]);
BufferedImage inImg = ImageIO.read(inFile);
int width = inImg.getWidth();
int height = inImg.getHeight();
int[] output = new int[width * height];
int[] pixels = inImg.getRaster().getPixels(0, 0, width, height, (int[])null);
double Gx;
double Gy;
double G;
for(i = 0 ; i < width ; i++ )
{
for(j = 0 ; j < height ; j++ )
{
if (i==0 || i==width-1 || j==0 || j==height-1)
G = 0;
else{
Gx = pixels[(i+1)*height + j-1] + 2*pixels[(i+1)*height +j] + pixels[(i+1)*height +j+1] -
pixels[(i-1)*height +j-1] - 2*pixels[(i-1)*height+j] - pixels[(i-1)*height+j+1];
Gy = pixels[(i-1)*height+j+1] + 2*pixels[i*height +j+1] + pixels[(i+1)*height+j+1] -
pixels[(i-1)*height+j-1] - 2*pixels[i*height+j-1] - pixels[(i+1)*height+j-1];
G = Math.hypot(Gx, Gy);
}
output[i*height+j] = (int)G;
}
}
BufferedImage outImg = new BufferedImage(width,height,BufferedImage.TYPE_BYTE_GRAY);
outImg.getRaster().setPixels(0,0,width,height,output);
FileOutputStream outFile = new FileOutputStream("result.jpg");
ImageIO.write(outImg,"JPG",outFile);
JFrame TheFrame = new JFrame("Result");
JLabel TheLabel = new JLabel(new ImageIcon(outImg));
TheFrame.getContentPane().add(TheLabel);
TheFrame.setSize(width, height);
TheFrame.addWindowListener(new WindowAdapter() {
public void windowClosing(WindowEvent e) {
System.exit(0);
}
});
TheFrame.setVisible(true);
它适用于方形图像,但当宽度 != 高度时,结果图像被破坏并且有一些对角线黑线。 :\
示例:
结果:
您的代码似乎期望 Raster.getPixels
在 列 中产生结果,如下所示:
0 3 6
1 4 7
2 5 8
但我相信它实际上是按行进行的,如下所示:
0 1 2
3 4 5
6 7 8
所以基本上,你目前有类似的东西:
pxy = pixels[x * height + y];
你应该
pxy = pixels[y * width + x];
例如,您有:
pixels[(i+1)*height + j-1]
你想要
pixels[(j-1)*width + i-1]
我尝试在 Java 中实现 Sobel 运算符,但结果只是混合了一些像素。
int i, j;
FileInputStream inFile = new FileInputStream(args[0]);
BufferedImage inImg = ImageIO.read(inFile);
int width = inImg.getWidth();
int height = inImg.getHeight();
int[] output = new int[width * height];
int[] pixels = inImg.getRaster().getPixels(0, 0, width, height, (int[])null);
double Gx;
double Gy;
double G;
for(i = 0 ; i < width ; i++ )
{
for(j = 0 ; j < height ; j++ )
{
if (i==0 || i==width-1 || j==0 || j==height-1)
G = 0;
else{
Gx = pixels[(i+1)*height + j-1] + 2*pixels[(i+1)*height +j] + pixels[(i+1)*height +j+1] -
pixels[(i-1)*height +j-1] - 2*pixels[(i-1)*height+j] - pixels[(i-1)*height+j+1];
Gy = pixels[(i-1)*height+j+1] + 2*pixels[i*height +j+1] + pixels[(i+1)*height+j+1] -
pixels[(i-1)*height+j-1] - 2*pixels[i*height+j-1] - pixels[(i+1)*height+j-1];
G = Math.hypot(Gx, Gy);
}
output[i*height+j] = (int)G;
}
}
BufferedImage outImg = new BufferedImage(width,height,BufferedImage.TYPE_BYTE_GRAY);
outImg.getRaster().setPixels(0,0,width,height,output);
FileOutputStream outFile = new FileOutputStream("result.jpg");
ImageIO.write(outImg,"JPG",outFile);
JFrame TheFrame = new JFrame("Result");
JLabel TheLabel = new JLabel(new ImageIcon(outImg));
TheFrame.getContentPane().add(TheLabel);
TheFrame.setSize(width, height);
TheFrame.addWindowListener(new WindowAdapter() {
public void windowClosing(WindowEvent e) {
System.exit(0);
}
});
TheFrame.setVisible(true);
它适用于方形图像,但当宽度 != 高度时,结果图像被破坏并且有一些对角线黑线。 :\
示例:
结果:
您的代码似乎期望 Raster.getPixels
在 列 中产生结果,如下所示:
0 3 6
1 4 7
2 5 8
但我相信它实际上是按行进行的,如下所示:
0 1 2
3 4 5
6 7 8
所以基本上,你目前有类似的东西:
pxy = pixels[x * height + y];
你应该
pxy = pixels[y * width + x];
例如,您有:
pixels[(i+1)*height + j-1]
你想要
pixels[(j-1)*width + i-1]