How to add annotation over image and save this annoted image using WPF.

You will need to use RenderTargetBitmap to draw the Image element and associated annotation adorners to disk. First I'd try just rendering the Image to the RTB and hope it draws the annotations too. If it does, you're done. If it does not, then you will need to figure out a way to loop over the annotation adorner controls and render them after you've rendered the Image element.