To get a better tell if the egg is fertile you can cut a hole in a large piece of card board, make sure the hole isn't bigger than the egg, set the piece of card board over the top of the lamp so light only shines through the hole & hold the egg over the hole. The light will only shine through the egg & you can see any fertile dark spots easier.
From what I can tell it looks like either the egg isn't fertile OR the pigeon hasn't been able to set on the egg long enough to start the embryo growing yet.