I am trying to convert sampleBuffer to a UIImage and display it in an image view with colorspaceGray. But it displays as the following image. I think there is a problem regarding the conversion. How can I convert the 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
})
}
The conversion is simple:
func captureOutput(_ captureOutput: AVCaptureOutput!, didOutputSampleBuffer sampleBuffer: CMSampleBuffer!, from connection: AVCaptureConnection!) {
let imageBuffer = CMSampleBufferGetImageBuffer(sampleBuffer)!
let ciimage = CIImage(cvPixelBuffer: imageBuffer)
let image = self.convert(cmage: ciimage)
}
// Convert CIImage to UIImage
func convert(cmage: CIImage) -> UIImage {
let context = CIContext(options: nil)
let cgImage = context.createCGImage(cmage, from: cmage.extent)!
let image = UIImage(cgImage: cgImage)
return image
}
The solutions above can now be improved further with new convenience methods on UIImage
. I have outlined below a modern solution also with image orientation correction. The solution doesn't use a CGImage
conversion, which improved runtime performance.
func orientation() -> UIImage.Orientation {
let curDeviceOrientation = UIDevice.current.orientation
var exifOrientation: UIImage.Orientation
switch curDeviceOrientation {
case UIDeviceOrientation.portraitUpsideDown: // Device oriented vertically, Home button on the top
exifOrientation = .left
case UIDeviceOrientation.landscapeLeft: // Device oriented horizontally, Home button on the right
exifOrientation = .upMirrored
case UIDeviceOrientation.landscapeRight: // Device oriented horizontally, Home button on the left
exifOrientation = .down
case UIDeviceOrientation.portrait: // Device oriented vertically, Home button on the bottom
exifOrientation = .up
default:
exifOrientation = .up
}
return exifOrientation
}
func captureOutput(_ captureOutput: AVCaptureOutput!, didOutputSampleBuffer sampleBuffer: CMSampleBuffer!, from connection: AVCaptureConnection!) {
guard let imageBuffer: CVPixelBuffer = CMSampleBufferGetImageBuffer(sampleBuffer) else { return }
let ciimage = CIImage(cvPixelBuffer: imageBuffer)
let image = UIImage(ciImage: ciimage, scale: 1.0, orientation: orientation())
}
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