CIGaussianBlur 质量：条带和伪影

Question

我正在尝试模糊 applicationWillResignActive 上的 AVCaptureVideoPreviewLayer，就像在股票 iOS Camera App 中一样。

由于光栅化 AVCaptureVideoPreviewLayer 和模糊本身会产生一个空帧，我通过从 didOutputSampleBuffer 和 applicationWillResignActive 保留一个 CIImage 来接近它，我把 CIImage -> Apply CIFilter CIGaussianBlur 添加到它，添加一个 UIImageView 到 AVCaptureVideoPreviewLayer 并使 UIImageView 的 图像成为我应用 CIGaussianBlur 的模糊的 UIImage 版本。

到目前为止，这似乎工作正常......但是，它似乎产生了相当多的条带，显示高斯模糊的质量问题。

抓取框架：

func captureOutput(captureOutput: AVCaptureOutput!, didOutputSampleBuffer sampleBuffer: CMSampleBuffer!, fromConnection connection: AVCaptureConnection!) {

            let imageBuffer = CMSampleBufferGetImageBuffer(sampleBuffer)
            CVPixelBufferLockBaseAddress(imageBuffer!, CVPixelBufferLockFlags(rawValue: CVOptionFlags(0)))

            let baseAddress = CVPixelBufferGetBaseAddress(imageBuffer!)

            let bytesPerRow = CVPixelBufferGetBytesPerRow(imageBuffer!)
            let width = CVPixelBufferGetWidth(imageBuffer!)
            let height = CVPixelBufferGetHeight(imageBuffer!)

            let colorSpace = CGColorSpaceCreateDeviceRGB()

            let bitmap = CGBitmapInfo(rawValue: CGBitmapInfo.ByteOrder32Little.rawValue|CGImageAlphaInfo.PremultipliedFirst.rawValue)
            let context = CGBitmapContextCreate(baseAddress, width, height, 8,
                                                bytesPerRow, colorSpace, bitmap.rawValue)
            let quartzImage = CGBitmapContextCreateImage(context!)
            CVPixelBufferUnlockBaseAddress(imageBuffer!,CVPixelBufferLockFlags(rawValue: CVOptionFlags(0)))

            self.cameraBufferImage = CIImage(CGImage: quartzImage!)
}

应用 CIGaussianBlur：

func blurPreviewWindow() {
    let previewLayer = self.previewView.layer as? AVCaptureVideoPreviewLayer
    previewLayer?.connection.enabled = false

    let context = CIContext(options: nil)
    let inputImage = self.cameraBufferImage!.imageByApplyingOrientation(6)

    let clampFilter = CIFilter(name: "CIAffineClamp")
    clampFilter!.setDefaults()
    clampFilter!.setValue(inputImage, forKey: "inputImage")

    if let currentFilter = CIFilter(name: "CIGaussianBlur") {
        currentFilter.setValue(clampFilter!.outputImage, forKey: "inputImage")
        currentFilter.setValue(50.0, forKey: "inputRadius")

        if let output = currentFilter.outputImage {
            if let cgimg = context.createCGImage(output, fromRect: inputImage.extent) {
                let processedImage = UIImage(CGImage: cgimg)
                self.previewBlurImageView = UIImageView(frame: self.previewView.bounds)
                self.previewBlurImageView?.alpha = 0
                self.previewView.addSubview(self.previewBlurImageView!)
                self.previewBlurImageView?.image = processedImage
                self.previewBlurImageView?.contentMode = .ScaleToFill
                self.previewBlurImageView?.layer.filters = [currentFilter]

                UIView.animateWithDuration(0.2, delay: 0.0, options: [.BeginFromCurrentState], animations: {
                                                () -> Void in
                    self.previewBlurImageView?.alpha = 1
                }, completion: { _ in })
            }
        }
    }
}

在这个 iOS 10 时代可能会有完全不同的方法吗？

更新：

这可能是色彩空间问题吗？由于测试设备是iPhone 7，颜色很广？

Answer 1

是 CIContext。

改变：

let context = CIContext(options: nil)

收件人：

let context = CIContext(options: [kCIContextWorkingColorSpace: CGColorSpaceCreateDeviceRGB(),
                                  kCIContextOutputColorSpace: CGColorSpaceCreateDeviceRGB(), 
                                  kCIContextUseSoftwareRenderer: false])

没有更多的条带或伪影！！！