Checking pixels from call to: grabPixels();

Question

I am using pixel grabber to grab the pixels in an image. Then once I have the pixels, I want to know how many of the pixels are Transparent.
I am loading a total transparent image to test with. The problem is that when I examine the contents of the array image_array, the values are all 0 (Zero ). This means the color of the pixel is black.
Which I think somehow equates to Transparent. But I thought transparent is: 0x01FF01
??? Help I am lost? Here is the code. I have included comments on
lines 23,25,26. Thanks in advance, Amy Danough
1 temp = getImage(getDocumentBase(),"sky.gif");
2 MediaTracker tracker = new MediaTracker(this);
3 tracker.addImage(temp,0);
4 try { tracker.waitForID(0);
5 }catch (InterruptedException e) {return;}
6
7
8 int widths = temp.getWidth(this);
9 int heights = temp.getHeight(this);
10 int[] image_array = new int[widths*heights];
11
12 try {tracker.waitForID(0);}
13 catch (InterruptedException e){}
14
15 PixelGrabber pg = new PixelGrabber(temp,0,0,widths,heights,image_array,0,widths);
16 try { pg.grabPixels(); }
17 catch (InterruptedException e) {}
18
19 int count = 0;
20 int rgb;
21 for (int i = 0; i < widths*heights; i++) {
22 rgb = image_array[i]; // get a pixel from the array
23 if (rgb == 0x01FF01){ count++; } // I am thinking tranpsarent == 0x01FF01
24 }
25 // Count always returns Zero for my totally transparent image.
// The value rgb at line 22 always equates to Zero ???

Answer 1

Don't use Toolkit.getImage()/createImage(), use javax.imageio.ImageIO.read(...)
or, if u do use the toolkit methods, copy the image into a BufferedImage before you start messing around with the pixels.
BufferedImage offers much better ways of maipulating the pixels directly. (without having to make a copy of them [which is what pixel grabber does])