How to replace color with another color in BufferedImage

Question

So I have an image file that has a volcano on it. Everything else is 0xFFFF00FF (opaque magenta). I want to replace every pixel that contains that color with 0 (transparent)

Answer 1

You can get the pixels[] array of the buffered image like so

int[] pixels = ((DataBufferInt) newImg().getDataBuffer()).getData();

and then set your colors like so

for (int i = 0; i < width; i++) {
    for (int j = 0; j < height; j++) {
        color = pixels[y * width + x];
        if (color == target) {
            pixels[y * width + x] = preferred;
        }
        else {
            pixels[y * width + x] = color;
        }
    }
}

This is a slight speed up over using setRGB()