This is an implementation of the Poisson Image Editing:
P. Prez, M. Gangnet, and A. Blake, Poisson image editing, ACM Transactions on Graphics (TOG), Vol. 22, No.3, pp. 313-318, 2003.
PoissonGaussSeidel is the implementation with the Gauss-Seidel algorithm. Actually, the implementation is SOR (Successive Over-Relaxation) algorithm.
PoissonJacobi is the implementation with the Jacobi algorithm.
PoissonGaussSeidel is much faster than PoissonJacobi.