Question

我在裁剪图像方面遇到了困难;目前有两件事情我想改进：

1）裁剪后，照片质量会下降。

2）拍摄照片后，方向视图不正确。

总结：发生的是，裁剪后的照片质量不正确标准，当图像出现在ImageView中时，它旋转90度;为什么会发生这些？我正在尝试根据捕获的流的视图裁剪图像。

以下是图像的裁剪：

  func crop(capture : UIImage) -> UIImage {

        let crop = cameraView.bounds

        //CGRect(x:0,y:0,width:50,height:50)

        let cgImage = capture.cgImage!.cropping(to: crop)

        let image : UIImage = UIImage(cgImage: cgImage!)

        return image
    }

这是我调用作物的地方

func capture(_ captureOutput: AVCapturePhotoOutput, didFinishProcessingPhotoSampleBuffer photoSampleBuffer: CMSampleBuffer?, previewPhotoSampleBuffer: CMSampleBuffer?, resolvedSettings: AVCaptureResolvedPhotoSettings, bracketSettings: AVCaptureBracketedStillImageSettings?, error: Error?) {
        if let photoSampleBuffer = photoSampleBuffer {
            let photoData = AVCapturePhotoOutput.jpegPhotoDataRepresentation(forJPEGSampleBuffer: photoSampleBuffer, previewPhotoSampleBuffer: previewPhotoSampleBuffer)
            var imageTaken = UIImage(data: photoData!)

            //post photo

            let croppedImage = self.crop(capture: imageTaken!)

            imageTaken = croppedImage
            self.imageView.image = imageTaken
           // UIImageWriteToSavedPhotosAlbum(imageTaken!, nil, nil, nil)
        }
    }

＆安培;这是全班

import UIKit
import AVFoundation

class CameraVC: UIViewController, UIImagePickerControllerDelegate, UINavigationControllerDelegate, AVCapturePhotoCaptureDelegate {

    var captureSession : AVCaptureSession?
    var stillImageOutput : AVCapturePhotoOutput?
    var previewLayer : AVCaptureVideoPreviewLayer?
    @IBOutlet weak var imageView: UIImageView!
    @IBOutlet var cameraView: UIView!

    override func viewDidLoad() {
        super.viewDidLoad()

        // Do any additional setup after loading the view.
    }

    override func viewDidLayoutSubviews() {
        super.viewDidLayoutSubviews()
        previewLayer?.frame = cameraView.bounds
    }

    override func viewWillAppear(_ animated: Bool) {
        super.viewWillAppear(animated)

        captureSession = AVCaptureSession()
        captureSession?.sessionPreset = AVCaptureSessionPreset1920x1080
        stillImageOutput = AVCapturePhotoOutput()

        let backCamera = AVCaptureDevice.defaultDevice(withMediaType: AVMediaTypeVideo)

        do {

            let input = try AVCaptureDeviceInput(device: backCamera)

            if (captureSession?.canAddInput(input))!{

                captureSession?.addInput(input)



                if (captureSession?.canAddOutput(stillImageOutput) != nil){
                    captureSession?.addOutput(stillImageOutput)

                    previewLayer = AVCaptureVideoPreviewLayer(session: captureSession)
                    previewLayer?.videoGravity = AVLayerVideoGravityResizeAspect
                    previewLayer?.connection.videoOrientation = AVCaptureVideoOrientation.portrait
                    cameraView.layer.addSublayer(previewLayer!)
                    captureSession?.startRunning()
                    let captureVideoLayer: AVCaptureVideoPreviewLayer = AVCaptureVideoPreviewLayer.init(session: captureSession!)
                    captureVideoLayer.frame = self.cameraView.bounds
                    captureVideoLayer.videoGravity = AVLayerVideoGravityResizeAspectFill
                    self.cameraView.layer.addSublayer(captureVideoLayer)



                }

            }

        } catch {

            print("An error has occured")

        }


    }

    @IBAction func takePhoto(_ sender: UIButton) {
        didPressTakePhoto()
    }

    func didPressTakePhoto(){

        if let videoConnection = stillImageOutput?.connection(withMediaType: AVMediaTypeVideo) {



            videoConnection.videoOrientation = AVCaptureVideoOrientation.portrait

            let settingsForCapture = AVCapturePhotoSettings()

            settingsForCapture.flashMode = .auto
            settingsForCapture.isAutoStillImageStabilizationEnabled = true
            settingsForCapture.isHighResolutionPhotoEnabled = false
            stillImageOutput?.capturePhoto(with: settingsForCapture, delegate: self)

        }


    }


    func capture(_ captureOutput: AVCapturePhotoOutput, didFinishProcessingPhotoSampleBuffer photoSampleBuffer: CMSampleBuffer?, previewPhotoSampleBuffer: CMSampleBuffer?, resolvedSettings: AVCaptureResolvedPhotoSettings, bracketSettings: AVCaptureBracketedStillImageSettings?, error: Error?) {
        if let photoSampleBuffer = photoSampleBuffer {
            let photoData = AVCapturePhotoOutput.jpegPhotoDataRepresentation(forJPEGSampleBuffer: photoSampleBuffer, previewPhotoSampleBuffer: previewPhotoSampleBuffer)
            var imageTaken = UIImage(data: photoData!)

            //post photo

            let croppedImage = self.crop(capture: imageTaken!)

            imageTaken = croppedImage
            self.imageView.image = imageTaken
           // UIImageWriteToSavedPhotosAlbum(imageTaken!, nil, nil, nil)
        }
    }


    func crop(capture : UIImage) -> UIImage {

        let crop = cameraView.bounds

        //CGRect(x:0,y:0,width:50,height:50)

        let cgImage = capture.cgImage!.cropping(to: crop)

        let image : UIImage = UIImage(cgImage: cgImage!)

        return image
    }

}

Answer 1

另一种方法是使用名为CIPerspectiveCorrect的Core Image过滤器。因为它使用了CIImage - 这不是一个真实的图像，而是一个＆＃34;配方＆＃34;对于图像 - 它不会遭受退化。

基本上，将你的UIImage / CGImage变成CIImage，挑选其中的任意4个点，并裁剪。它不需要是平行四边形（或CGRect），只需要4个点。使用CI过滤器时有两个不同的注意事项：

您使用CIVector而不是使用CGRect。根据滤波器，矢量可以具有2,3,4，甚至更多参数。在这种情况下，您需要4个CIVectors，每个参数有2个参数，对应于左上角（TL），右上角（TR），左下角（BL）和右下角（BR）。
CI图像的左下角有原点（X / Y == 0/0），而不是左上角。这基本上意味着您的Y坐标从CG或UI图像上下颠倒。

这是一些示例代码。首先，一些示例声明，包括CI上下文：

let uiTL = CGPoint(x: 50, y: 50)
let uiTR = CGPoint(x: 75, y: 75)
let uiBL = CGPoint(x: 100, y: 300)
let uiBR = CGPoint(x: 25, y: 200)

var ciImage:CIImage!
var ctx:CIContext!

@IBOutlet weak var imageView: UIImageView!

在viewDidLoad中我们设置上下文并从UIImageView获取我们的CIImage：

override func viewDidLoad() {
    super.viewDidLoad()
    ctx = CIContext(options: nil)
    ciImage = CIImage(image: imageView.image!)
}

UIImageViews有一个框架或CGRect，UIImages有一个大小或CGSize。 CIImages有一定程度，基本上就是你的CGSize。但请记住，Y轴是翻转的，并且可以无限延伸！（虽然这不是UIImage源码的主要内容。）这里有一些辅助功能来转换东西：

func createScaledPoint(_ pt:CGPoint) -> CGPoint {
    let x = (pt.x / imageView.frame.width) * ciImage.extent.width
    let y = (pt.y / imageView.frame.height) * ciImage.extent.height
    return CGPoint(x: x, y: y)
}
func createVector(_ point:CGPoint) -> CIVector {
    return CIVector(x: point.x, y: ciImage.extent.height - point.y)
}
func createPoint(_ vector:CGPoint) -> CGPoint {
    return CGPoint(x: vector.x, y: ciImage.extent.height - vector.y)
}

这是对CIPerspectiveCorrection的实际调用。如果我没记错的话，Swift 3的改变就是使用AnyObject。虽然更强类型的变量在以前版本的Swift中有效，但它们现在会导致转储：

func doPerspectiveCorrection(
    _ image:CIImage,
    context:CIContext,
    topLeft:AnyObject,
    topRight:AnyObject,
    bottomRight:AnyObject,
    bottomLeft:AnyObject)
    -> UIImage {
        let filter = CIFilter(name: "CIPerspectiveCorrection")
        filter?.setValue(topLeft, forKey: "inputTopLeft")
        filter?.setValue(topRight, forKey: "inputTopRight")
        filter?.setValue(bottomRight, forKey: "inputBottomRight")
        filter?.setValue(bottomLeft, forKey: "inputBottomLeft")
        filter!.setValue(image, forKey: kCIInputImageKey)
        let cgImage = context.createCGImage((filter?.outputImage)!, from: (filter?.outputImage!.extent)!)
        return UIImage(cgImage: cgImage!)
}

现在我们有了CIImage，我们创建了四个CIVectors。在这个示例项目中，我对4个CGPoints进行了硬编码，并选择在viewWillLayoutSubviews中创建CIVector，最早的我有UI框架：

override func viewWillLayoutSubviews() {
    let ciTL = createVector(createScaledPoint(uiTL))
    let ciTR = createVector(createScaledPoint(uiTR))
    let ciBR = createVector(createScaledPoint(uiBR))
    let ciBL = createVector(createScaledPoint(uiBL))
    imageView.image = doPerspectiveCorrection(CIImage(image: imageView.image!)!,
                                              context: ctx,
                                              topLeft: ciTL,
                                              topRight: ciTR,
                                              bottomRight: ciBR,
                                              bottomLeft: ciBL)
}

如果您将此代码放入项目中，请将图像加载到UIImageView中，找出您想要的4个CGPoints并运行它，您应该会看到加盖的图像。祝你好运！

Answer 2

添加到@dfd回答。如果您不想使用精美的核心图像过滤器，请按照此处的工作进行操作。

拍摄后的照片质量很差？

虽然您使用了最高可能的会话预设AVCaptureSessionPreset1920x1080，但您正在将样本图像缓冲区转换为JPEG格式，然后对其进行裁剪。显然质量会有一些损失。为了获得高质量的裁剪图像，请尝试会话预设AVCaptureSessionPresetHigh以让AVFoundation决定高质量视频，并dngPhotoDataRepresentation(forRawSampleBuffer:previewPhotoSampleBuffer:)以DNG格式获取图片。
拍摄照片后视图和方向不正确？

didFinishProcessingPhotoSampleBuffer委托给你的样本缓冲区始终向左旋转90度。所以你可能想要自己旋转90度。

使用cgImage和方向为正确初始化你的UIImage并缩放为1.0。

init(cgImage: CGImage, scale: CGFloat, orientation: UIImageOrientation)

裁剪图像的问题

2 个答案: