Android grayscale ColroMatrixFilter

gistfile1.java

// grayscale color filter

float r = 0.298912F;
float g = 0.586611F;
float b = 0.114478F;

ColorMatrixFilter filter = new ColorMatrixFilter(
        new ColorMatrix(new float[] {
            r, g, b, 0, 0,
            r, g, b, 0, 0,
            r, g, b, 0, 0,
            0, 0, 0, 1, 0
        }));