ios - CIFilter won't apply filter at touch location -

i using code below apply image filter touch location set radius, filter being placed in wrong spot. x coordinate seems close, y coordinate reversed , 400+ pixels off touch. if move finger up, filter moves down , opposite. using kciinputcenterkey : civector parameter incorrectly? how place center of filter radius @ touch location?

override func touchesmoved(touches: set<uitouch>, withevent event: uievent?) {      let filter = cifilter(name: "cipixellate")!     let inputimage = ciimage(image: originalimage)!     filter.setvalue(inputimage, forkey: kciinputimagekey)     let fullpixellatedimage = filter.outputimage     var maskimage: ciimage!     let radialgradient = cifilter(name: "ciradialgradient",         withinputparameters: [             "inputradius0" : 30,             kciinputcenterkey : civector(x: (touches.first?.locationinview(self.view).x)!, y: (touches.first?.locationinview(self.view).y)!)         ])!     let radialgradientoutputimage = radialgradient.outputimage!.imagebycroppingtorect(inputimage.extent)     if maskimage == nil {         maskimage = radialgradientoutputimage     } else {         maskimage = cifilter(name: "cisourceovercompositing",             withinputparameters: [                 kciinputimagekey : radialgradientoutputimage,                 kciinputbackgroundimagekey : maskimage             ])!.outputimage     }     let blendfilter = cifilter(name: "ciblendwithmask")!     blendfilter.setvalue(fullpixellatedimage, forkey: kciinputimagekey)     blendfilter.setvalue(inputimage, forkey: kciinputbackgroundimagekey)     blendfilter.setvalue(maskimage, forkey: kciinputmaskimagekey)     let blendoutputimage = blendfilter.outputimage!     let blendcgimage = context.createcgimage(blendoutputimage, fromrect: blendoutputimage.extent)     mainimageview.image = uiimage(cgimage: blendcgimage)  }