★★★★★
My aunt had melasma. She started ding Kapalbhati pranayam and the melasma reduced within a few weeks and went away completely in a couple of months. In India, yoga master Ramdev Baba's style of doing kapalbhati Pranayam is the most popular. Here is the link to see how it is done:
http://knowyoga.org/tiki-index.php?page=Kapal Bhati Pranayam
If you do it, do write back in a month to let us all know if your melasma has faded. Good wishes! (I do kapalbhati everyday for other health benefits and like Ramdev Baba says, it seems to cure all problems.)