Unsharp mask filter for iPad

Hi friends,

I am trying to apply USM filter on the image (taking from the server). but i am not getting any help in apple document. I searched in google and i got GPUIimage and imagemagick open source library. but in imagemagick it seems USM filter is not working and in GPUIimage, i am not getting how it will take image as input which i am taking from the server .

please guide me.

Thanks