How to apply black and white filter on image using BufferedImageOp?

Question

I do have this code to increase the sharpness of the image using BufferedImageOp

class DecreaseSharpenFilter implements MyFilter{
    public BufferedImage processImage(BufferedImage image) {
        float[] decreaseSharpnessMatrix = {0.0f, +1.0f, 0.0f, +1.0f , -5.0f, +1.0f, 0.0f, +1.0f, 0.0f };
         BufferedImageOp DecreaseSharpenFilter = new ConvolveOp(new Kernel(3, 3, decreaseSharpnessMatrix),
                    ConvolveOp.EDGE_NO_OP, null);
                return DecreaseSharpenFilter.filter(image, null);
    }
}

Now I want to convert image to black and white by doing modifications to these lines but I don't really know what values to use in the matrix and how to convolve it.

Answer 1

You just need to make a colorspace, then pass it in to your convertOP

ColorSpace cs = ColorSpace.getInstance(ColorSpace.CS_GRAY);  
ColorConvertOp op = new ColorConvertOp(cs, null);
BufferedImage image = op.filter(image, null);