What is the expiation for a strange man photographing a recently married woman in her wedding dress?

The sister must repent to Allah the Almighty, for it is not permissible for her to display her adornment before non-mahram men in photography or otherwise, due to the Almighty's saying: "And not display their adornment except that which is apparent thereof." And in the case of sincere repentance, Allah forgives whoever turns to Him, for "The one who repents from sin is like the one who has no sin," and there is no specific expiation for this act, but one should increase in supererogatory acts and good deeds after maintaining the obligatory ones.