Antialiasing text on canvas

I have to create .pngs for a lot of clients that are printed by an industrial inkjet (ads on back of a children's magazines).

Unfortunately, all browsers seem to switch on antialiasing - no matter what I try. Neither CSS nor ctx.mozImageSmoothingEnabled=false; seem to work.

Does anyone have any idea to get text displayed on canvas WITHOUT any grey-scaled pixels trying to make the font sharper?