Make an image darker

Question

Hi all !
I was looking for making a transparent background using a frame.
I have a screen resolution of 1600 by 600, but my application uses
the left part of the screen (800 x 600).
Now that I have captured the screen, I want to make it darker,
so the user can distinguish reel icons from the application surface.
I've (almost) never worked using images.
Question : How can I display a darker image than the one I've captured ?
Can somebody help me for my quest ?

Answer 1

// This parameter changes how much you darken the image
float brightnessRatio = 0.8f;
// Get an image producer for the image
ImageProducer ip = img.getSource();
// Construct a suitable filter
RGBImageFilter filter = new RGBImageFilter()
        boolean canFilterIndexColorModel = false;
        public int filterRGB(int x, int y, int rgb)
            // Extract the individual fields
            int red = ((rgb & 0x00ff0000) >> 16);
            int green = ((rgb & 0x0000ff00) >> 8);
            int blue = (rgb & 0x000000ff);
            // Get the HSB equivalent values
            float[] hsb = Color.RGBtoHSB(red, green, blue, null);
            // Use the brightness to code up a grey
            int return_value = Color.HSBtoRGB(hsb[0],
                                              hsb[1],
                                              hsb[2] * brightnessRatio);
            return return_value;
// Create an image producer for the filtered image
ImageProducer filt_ip = new FilteredImageSource(ip,
                                                filter);
// Produce the output image
out_img = getToolkit().createImage(filt_ip);