A useful function of many imaging programs such as GIMP is its ability to make only one color of an Image transparent; this is called applying a mask. To do this, GIMP evaluates each pixel of an image, and tests if it is the user specified masking color, if it is it sets that pixel's RGB value to nothing, and it's alpha to 0.0. Here is the Java implementation:
public static BufferedImage makeColorTransparent(String ref, Color color) {
BufferedImage image = loadImage(ref);
BufferedImage dimg = new BufferedImage(image.getWidth(), image.getHeight(), BufferedImage.TYPE_INT_ARGB);
Graphics2D g = dimg.createGraphics();
g.setComposite(AlphaComposite.Src);
g.drawImage(image, null, 0, 0);
g.dispose();
for(int i = 0; i < dimg.getHeight(); i++) {
for(int j = 0; j < dimg.getWidth(); j++) {
if(dimg.getRGB(j, i) == color.getRGB()) {
dimg.setRGB(j, i, 0x8F1C1C);
}
}
}
return dimg;
}
This grabs the Graphics2D instance of the destination image, and sets it's composite to Alpha. It then draws the Image onto the screen, and disposes of the Graphics2D to clear up system resources. Next, it cycles through all the pixels in the image, using the for loops, and compares the color of the pixel to the mask color. If the pixels color matches the mask color, that pixels color is replaced by an alpha RGB value. Lastly, the destination image, with mask applied, is returned.
Running Codes
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