当我运行这个应该检测图像中的圆圈的程序时，当我调用 drawCircles() 时，我在最后一个方法中得到 Array index out of bounds 异常
findCircle() 读取图像并搜索圆圈，然后 drawCircles() 使用 Bresenaham 算法绘制它们。
public class Assig1 {
public static void main(String[] args) {
try {
// arg 0 is the input image name
BufferedImage img = ImageIO.read(new File(args[0]));
// arg 1 is the min radius
int minr = Integer.parseInt(args[1]);
// arg 2 is the max radius
int maxr = Integer.parseInt(args[2]);
// if present, arg 3 is the max width we consider
int w = (args.length>3) ? Integer.parseInt(args[3]) : img.getWidth();
// if present, arg 4 is the max height we consider
int h = (args.length>4) ? Integer.parseInt(args[4]) : img.getHeight();
// you can look at pixel values with this API call:
int c = img.getRGB(0,0); // get RGB value of pixel at (0,0)
// you can write out pixels with the setRGB() API. However,
// what you get will depend on the colour model, so here
// we use a Graphics2D object.
// graphical output
Graphics2D g2 = img.createGraphics();
// use red
g2.setColor(Color.RED);
// call circle drawing algorithm
drawCircle(5,5,3,img,g2);
//-----
findCircle(minr,img, w, h);
//----
// write out the image
File outputfile = new File("outputimage1.png");
ImageIO.write(img, "png", outputfile);
} catch (Exception e) {
e.printStackTrace();
}
}
// Bresenham's algorithm to draw a circle
// requires circle center and radius, as well as the
// image and Graphics2D object with drawing colour already set.
static void drawCircle(int cx,int cy,int r,BufferedImage img,Graphics2D g) {
int f = 1-r;
int ddF_x = 1;
int ddF_y = -2 * r;
int x = 0;
int y = r;
// draw cardinal points
g.drawLine(cx,cy+r,cx,cy+r);
g.drawLine(cx,cy-r,cx,cy-r);
g.drawLine(cx+r,cy,cx+r,cy);
g.drawLine(cx-r,cy,cx-r,cy);
// draw 1/8 of the circle, taking advantage of symmetry
while(x < y) {
if(f >= 0) {
y--;
ddF_y += 2;
f += ddF_y;
}
x++;
ddF_x += 2;
f += ddF_x;
g.drawLine(cx+x,cy+y,cx+x,cy+y);
g.drawLine(cx-x,cy+y,cx-x,cy+y);
g.drawLine(cx+x,cy-y,cx+x,cy-y);
g.drawLine(cx-x,cy-y,cx-x,cy-y);
g.drawLine(cx+y,cy+x,cx+y,cy+x);
g.drawLine(cx-y,cy+x,cx-y,cy+x);
g.drawLine(cx+y,cy-x,cx+y,cy-x);
g.drawLine(cx-y,cy-x,cx-y,cy-x);
}
}
static void findCircle(int r,BufferedImage img, int w, int h) {
//getting all the pixels from an image
int[][] pixels = new int[w][h];
for( int i = 0; i < w; i++ ){
for( int j = 0; j < h; j++ ){
pixels[i][j] = img.getRGB( i, j );
}
}
// graphical output
Graphics2D g2 = img.createGraphics();
// use red
g2.setColor(Color.RED);
for (int i1=0; i1<pixels.length; i1++) {
for (int j1=0; j1<pixels[i1].length; j1++) {
if(pixels[i1][j1] != pixels[i1+r][j1]
|| pixels[i1][j1] != pixels[i1-r][j1]
|| pixels[i1][j1] != pixels[i1][j1+r]
|| pixels[i1][j1] != pixels[i1][j1-r]){
drawCircle(i1,j1,r,img,g2);
}
}
}
}
}