float[] matrix = {
    1/16f, 1/8f, 1/16f, 
    1/8f, 1/4f, 1/8f, 
    1/16f, 1/8f, 1/16f, 
};

BufferedImageOp op = new ConvolveOp( new Kernel(3, 3, matrix) );
blurredImage = op.filter(sourceImage, destImage);