I want to get rid of the border in my dialog box and make it look absolutly transparent, as if the image is on the top of screen.
To give a translucent effect, say 50% opacity, use:
Drawable d = new ColorDrawable(Color.BLACK); d.setAlpha(130); mDialog.getWindow().setBackgroundDrawable(d);
'130' can be changed (0-255) to acheive desired opacity.