[Java/Android] Convert a Picture from an ImageView into GrayScale

convertToGrayScale.java

// Convert Imageview to grayscale
private void convertToGrayScale(ImageView imageView, boolean convert) {
    if (!convert) {
        ColorMatrix matrix = new ColorMatrix();
        matrix.setSaturation(0);

        ColorMatrixColorFilter filter = new ColorMatrixColorFilter(matrix);
        imageView.setColorFilter(filter);
    } else {
        imageView.setColorFilter(null);
    }
}