Pretty sure this *is* supposed to be Andromeda. She was supposed to have been chained to a rock by the sea, naked, as a sacrifice to a sea monster. It's a scene that's been depicted in a lot of classical artwork, though not quite like this.
Indeed. Her mother supposedly boasted that she was more beautiful then the Nereids so she ended up tied up to be a sacrifice. Although I highly doubt that they would have tied her like this.