File file = new File("F:/firefox.png");File destFile = new File("F:/pic/" + System.currentTimeMillis() + ".png");BufferedImage image = ImageIO.read(file);BufferedImage destImage = new BufferedImage(image.getWidth(), image.getHeight(), BufferedImage.TYPE_INT_ARGB);ColorConvertOp cco = new ColorConvertOp(ColorSpace.getInstance(ColorSpace.CS_GRAY), null);cco.filter(image, destImage);ImageIO.write(destImage, "png", destFile);