I want to read in a jpeg image with a uniform gray background with several colored balls on it of the same size. I want a program which can take this image and record the coordinates of each ball. whats the best way to do this?
A:
You can use the ImageIO library to read in an image by using one of the read() methods. This produces a BufferedImage which you can analyze for the separate colors. getRGB() is probably the best way to do this. You can compare this to the getRGB() of a Color object if you need to. That should be enough to get you started.
James
2009-06-26 19:50:29
+1
A:
I agree with James. I used the following program once to find red boxes in an image (before most of the red boxes were recolored by the community):
/**
* @author karnokd, 2008.11.07.
* @version $Revision 1.0$
*/
public class RedLocator {
public static class Rect {
int x;
int y;
int x2;
int y2;
}
static List<Rect> rects = new LinkedList<Rect>();
static boolean checkRect(int x, int y) {
for (Rect r : rects) {
if (x >= r.x && x <= r.x2 && y >= r.y && y <= r.y2) {
return true;
}
}
return false;
}
public static void main(String[] args) throws Exception {
BufferedImage image = ImageIO.read(new File("fallout3worldmapfull.png"));
for (int y = 0; y < image.getHeight(); y++) {
for (int x = 0; x < image.getWidth(); x++) {
int c = image.getRGB(x,y);
int red = (c & 0x00ff0000) >> 16;
int green = (c & 0x0000ff00) >> 8;
int blue = c & 0x000000ff;
// check red-ness
if (red > 180 && green < 30 && blue < 30) {
if (!checkRect(x, y)) {
int tmpx = x;
int tmpy = y;
while (red > 180 && green < 30 && blue < 30) {
c = image.getRGB(tmpx++,tmpy);
red = (c & 0x00ff0000) >> 16;
green = (c & 0x0000ff00) >> 8;
blue = c & 0x000000ff;
}
tmpx -= 2;
c = image.getRGB(tmpx,tmpy);
red = (c & 0x00ff0000) >> 16;
green = (c & 0x0000ff00) >> 8;
blue = c & 0x000000ff;
while (red > 180 && green < 30 && blue < 30) {
c = image.getRGB(tmpx,tmpy++);
red = (c & 0x00ff0000) >> 16;
green = (c & 0x0000ff00) >> 8;
blue = c & 0x000000ff;
}
Rect r = new Rect();
r.x = x;
r.y = y;
r.x2 = tmpx;
r.y2 = tmpy - 2;
rects.add(r);
}
}
}
}
}
}
Might give you some hints. The image originates from here.
kd304
2009-06-26 19:52:44