Image Border

import CoreImage
import CoreImage.CIFilterBuiltins
import UIKit


let testImage = UIImage(named: "test")!
let inputImage = CIImage(cgImage: testImage.cgImage!)

let filter = CIFilter.morphologyMinimum()
filter.inputImage = inputImage
filter.radius = 10

let outputImage = filter.outputImage!.cropped(to: inputImage.extent)

let output = UIImage(ciImage: outputImage)