Stamping Decoupage

How can I decoupage on glass so that the glass can be rewashed?
I received some beautiful wrapping paper images that I would like to use on some plain white coffee mugs. Each image is about the size of a postage stamp, and I would only use 1 or 2 images per coffee mug. Does anyone know what type of glue and varnish to use? The mugs would be hand-washed, not to use in the dishwasher, but I don't want the image to be damaged when the mug needs to be washed. I know how to paint on glass, but I am new to decoupage on glass!
I'm sorry, but there is no real piratical way to apply them to mugs that will be used as the way you have mentioned. Decoupage is usually used for decorative purposes only. There are mugs that you insert pictures inside a double wall. They are often sold to insert children's pictures inside. Maybe one of these, with some adjustments, might work for you.