Maybe this will help you:
http://docs.oracle.com/javase/7/docs/api/java/awt/image/BufferedImage.html
http://docs.oracle.com/javase/7/docs/api/javax/imageio/ImageIO.html
BufferedImage img = ImageIO.read(new File("filePath.png"));
int sRbgColor = img.getRGB(int x, int y);
Color c = new Color(sRbgColor);
int red = c.getRed();
int green = c.getGreen();
int blue = c.getBlue();
If it's monochrome, then red green and blue should be equal.