Image processing in wp7

Question

I am new in windows phone development , i am creating an application in which i require some effects over an image such as sketch effect , twist a image , skew a image , alien face mask effect etc.

I am referring this app for my development

http://www.windowsphone.com/en-us/store/app/photo-warp-free/8ac66843-6477-4837-b31e-bef608a7eb82

how to implement the effects used in the app above?

Thanks in advance