将CMSampleBuffer转换为UIImage

Question

我正在尝试将sampleBuffer转换为UIImage并使用colorspaceGray在图像视图中显示它。但它显示为以下图像。我认为转换存在问题。如何转换CMSampleBuffer？

func captureOutput(_ captureOutput: AVCaptureOutput!, didOutputSampleBuffer sampleBuffer: CMSampleBuffer!, from connection: AVCaptureConnection!) {
    print("buffered")
    let imageBuffer: CVImageBuffer = CMSampleBufferGetImageBuffer(sampleBuffer)!
    CVPixelBufferLockBaseAddress(imageBuffer, CVPixelBufferLockFlags(rawValue: 0))
    let width: Int = CVPixelBufferGetWidth(imageBuffer)
    let height: Int = CVPixelBufferGetHeight(imageBuffer)
    let bytesPerRow: Int = CVPixelBufferGetBytesPerRow(imageBuffer)
    let lumaBuffer = CVPixelBufferGetBaseAddress(imageBuffer)

    //let planeCount : Int = CVPixelBufferGetPlaneCount(imageBuffer)
    let grayColorSpace: CGColorSpace = CGColorSpaceCreateDeviceGray()
    let context: CGContext = CGContext(data: lumaBuffer, width: width, height: height, bitsPerComponent: 8, bytesPerRow: bytesPerRow , space: grayColorSpace, bitmapInfo: CGImageAlphaInfo.none.rawValue)!
    let dstImageFilter: CGImage = context.makeImage()!
    let imageRect : CGRect = CGRect(x: 0, y: 0, width: width, height: height)
    context.draw(dstImageFilter, in: imageRect)
    let image = UIImage(cgImage: dstImageFilter)
    DispatchQueue.main.sync(execute: {() -> Void in
        self.imageTest.image = image
    })
}

Answer 1

转换很简单：

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

     let imageBuffer: CVPixelBuffer = CMSampleBufferGetImageBuffer(sampleBuffer)!
     let ciimage : CIImage = CIImage(cvPixelBuffer: imageBuffer)   
     let image : UIImage = self.convert(cmage: ciimage) 
}

// Convert CIImage to CGImage
func convert(cmage:CIImage) -> UIImage
{
     let context:CIContext = CIContext.init(options: nil)
     let cgImage:CGImage = context.createCGImage(cmage, from: cmage.extent)!
     let image:UIImage = UIImage.init(cgImage: cgImage)
     return image
}

Answer 2

看起来CMSampleBuffer正在为您提供RGBA数据，然后您可以直接构建灰度图像。您将需要构建一个新的缓冲区，对于每个像素，您执行gray = (pixel.red+pixel.green+pixel.blue)/3之类的操作。或者您需要根据收到的数据创建一个普通的RGBA图像，然后将其转换为灰度。

但是在你的代码中你根本没有过渡。你使用CVPixelBufferGetBaseAddress将原始指针带到缓冲区，而不管那里有什么类型的数据。然后你只需在创建图像时传递相同的指针，该图像假定接收的数据是灰度的。