Detect faces and apply pixellate filter on it

main.swift

#!/usr/bin/swift
//
//  main.swift
//  Anonymizer
//
//  Created by sooopd on 2018. 3. 30..
//  Copyright © 2018년 sooopd. All rights reserved.
//

import Cocoa
import CoreImage
import Vision

/// find facial feature and process it
func detectFaces(in source: CIImage, completionHandler:((CIImage) -> Void)?)
{
    let request = VNDetectFaceLandmarksRequest { req, error in
        guard error == nil else {
            NSLog("Error: \(error!.localizedDescription)")
            return
        }
        
        guard let results = req.results as? [VNFaceObservation] else {
            NSLog("Fail: Not supported result type.")
            return
        }
        
        print("> found \(results.count) faces in the image")
        print("> anonymizing...")
        
        // Create Reulst Image
        let boundingBoxes = results.map{ $0.boundingBox }
        let resultImage = createAnonymizedImage(from: source,
                                                boundingBoxes: boundingBoxes)
        
        // call completeionHandler
        completionHandler?(resultImage)
    }
    
    let handler = VNImageRequestHandler(ciImage: source,
                                        options: [:])
    try? handler.perform([request])
}

func createAnonymizedImage(from source: CIImage, boundingBoxes: [CGRect]) -> CIImage
{
    let (imageWidth, imageHeight): (Int, Int) = {
        let size = source.extent.size
        return (Int(size.width), Int(size.height))
    }()
     
    // Create Bitmap Context
    let maskImage: CIImage = {
        let ctx = CGContext(data: nil,
                            width: imageWidth,
                            height: imageHeight,
                            bitsPerComponent: 8,
                            bytesPerRow: 0,
                            space: CGColorSpaceCreateDeviceGray(),
                            bitmapInfo: CGImageAlphaInfo.none.rawValue)!
        ctx.setFillColor(NSColor.white.cgColor)
        // fill(_ rects:) 를 사용하여 얼굴 영역을 칠한다.
        ctx.fill(boundingBoxes.map{VNImageRectForNormalizedRect($0, imageWidth, imageHeight)})
        return CIImage(cgImage: ctx.makeImage()!)
    }()
    
    let inputImage = source.applyingFilter("CIPixellate", parameters:
        [kCIInputScaleKey: 18.0])
    
    let resultImage = inputImage.applyingFilter("CIBlendWithMask", parameters:
        [kCIInputMaskImageKey: maskImage,
         kCIInputBackgroundImageKey: source])
    
    return resultImage
}

func main() {
    guard case let arguments = CommandLine.arguments, arguments.count > 1
        else {
            print("Usage: anonymizer <filepath>")
            return
    }
    
    let context = CIContext()
    
    if case let fileURL = URL(fileURLWithPath:(arguments[1] as NSString).expandingTildeInPath),
        let image = CIImage(contentsOf:fileURL)
    {
        
        let saveFileURL: URL = {
            let filename = fileURL.lastPathComponent
            let path = fileURL.deletingLastPathComponent()
            return path.appendingPathComponent("anony-\(filename).png")
        }()
        
        print("Analyze Image...")
        detectFaces(in: image){ resultImage in
            
            defer {
                DispatchQueue.main.async{
                    CFRunLoopStop(CFRunLoopGetMain())
                }
            }
            print("Trying to save processed file.")
            do {
                try context.writePNGRepresentation(
                    of: resultImage,
                    to: saveFileURL,
                    format: kCIFormatARGB8,
                    colorSpace: CGColorSpaceCreateDeviceRGB(),
                    options: [:])
                print("Complete.")
            } catch {
                fatalError("Fail to write image data.")
            }
        }
        CFRunLoopRun()
    }
}

main()