An invention is disclosed for performing differencing of graphical data in post-transform space for a remote presentation session. Graphical data is transformed from a first representation to a second representation (e.g. with a DWT), and then a difference is taken of the post-transform data and the post-transform data of the frame that preceded the current frame. This difference is then encoded and transmitted to a client, which decodes it, and creates a representation of the graphical data using the delta, and a previously determined representation of the previous frame. By performing differencing in post-transform space, fidelity of the remote presentation session is retained while it may decrease bandwidth. This may occur because the entropy of the delta representation is usually lower than a non-delta representation while the scheme retains the identical data of the final decoded image of the non-delta version of the same compression scheme.