How might I add a watermark effect to an image in Android?

For others reference, if you want to add the logo of your application (which is in your drawable folder(s)) on top of image use following method:

private Bitmap addWaterMark(Bitmap src) {
        int w = src.getWidth();
        int h = src.getHeight();
        Bitmap result = Bitmap.createBitmap(w, h, src.getConfig());
        Canvas canvas = new Canvas(result);
        canvas.drawBitmap(src, 0, 0, null);

        Bitmap waterMark = BitmapFactory.decodeResource(mContext.getResources(), R.drawable.logo);
        canvas.drawBitmap(waterMark, 0, 0, null);

        return result;
    }

I found great tutorial on Android Image Processing here.

public static Bitmap mark(Bitmap src, String watermark, Point location, Color color, int alpha, int size, boolean underline) {
    int w = src.getWidth();
    int h = src.getHeight();
    Bitmap result = Bitmap.createBitmap(w, h, src.getConfig());

    Canvas canvas = new Canvas(result);
    canvas.drawBitmap(src, 0, 0, null);

    Paint paint = new Paint();
    paint.setColor(color);
    paint.setAlpha(alpha);
    paint.setTextSize(size);
    paint.setAntiAlias(true);
    paint.setUnderlineText(underline);
    canvas.drawText(watermark, location.x, location.y, paint);

    return result;
}

Thanks to Pete Houston who shares such useful tutorial on basic image processing.