How to determine color of an image with code.

Question

Hello,
I need to determine if an image is of a particular color. Ideally I might eventually like to determine what percentage of the image is of a particular color. For example if you have a picture of a redish, yellow and blue sky, it would be nice to know what percentage of the image is red. Or if determining the percentage takes up too much processing time, I could just determine if a rectangular sub region of the image is red.
How can this be done? Here are two of the line of code I am using to store the image.
private Image myImage;
myImage = getImage(getDocumentBase(), "SkyImg.gif");
Also, does anyone know if this takes up much processing time?
I need to repeatedly check the color at various times in a particular
time period and I need the process to be as fast as possible. I would
sincerely appreciate the help.

Answer 1

HI,
would be something along these lines:
    public void color_finder() {
        Image temp = null;
        int width = temp.getWidth();
        int height = temp.getHeight();
        int[] image_array = new int[width*height];
        try {
            temp = ImageIO.read(getClass().getResource("image.gif"));
        } catch (IOException ioe) {}
        MediaTracker tracker = new MediaTracker(this);
        tracker.addImage(temp,0);
        try   {tracker.waitForID(0);}
        catch (InterruptedException e){}
        pg = new PixelGrabber(tempmap,0,0,width,height,image_array,0,width);
        try { pg.grabPixels(); }
        catch (InterruptedException e) {}
        int count = 0;
        for (int i = 0; i < width*height; i++) {
            if (image_array.isLegalColor()) count++;
int percent = (count/(width*height))*100;
//blah blah