Question

I have two BufferedImages I loaded in from pngs. The first contains an image, the second an alpha mask for the image.

I want to create a combined image from the two, by applying the alpha mask. My google-fu fails me.

I know how to load/save the images, I just need the bit where I go from two BufferedImages to one BufferedImage with the right alpha channel.

Answer 1

Your solution could be improved by fetching the RGB data more than one pixel at a time(see http://java.sun.com/javase/6/docs/api/java/awt/image/BufferedImage.html), and by not creating three Color objects on every iteration of the inner loop.

final int width = image.getWidth(); int[] imgData = new int[width]; int[] maskData = new int[width];  for (int y = 0; y < image.getHeight(); y++) {     // fetch a line of data from each image     image.getRGB(0, y, width, 1, imgData, 0, 1);     mask.getRGB(0, y, width, 1, maskData, 0, 1);     // apply the mask     for (int x = 0; x < width; x++) {         int color = imgData[x] & 0x00FFFFFF; // mask away any alpha present         int maskColor = (maskData[x] & 0x00FF0000) << 8; // shift red into alpha bits         color |= maskColor;         imgData[x] = color;     }     // replace the data     image.setRGB(0, y, width, 1, imgData, 0, 1); }