Distorted CVImageBuffer to UIImage - ios

Question

I have the following function that converts CVImageBugger to UIImage. The image that comes out is always a little bit distorted. I display the return value of this function in a UIImageView, which is set to 'aspect fill'. What gives?...
private func convert(buffer: CVImageBuffer) -> UIImage? {
let cmage: CIImage = CIImage(cvPixelBuffer: buffer)
let context: CIContext = CIContext(options: nil)
if let cgImage: CGImage = context.createCGImage(cmage, from: cmage.extent) {
return UIImage(cgImage: cgImage)
}
return nil
}

Answer 1

The CVImageBuffer doesn't contain the orientation information, maybe that's why the final UIImage is distorted.
The default orientation of CVImageBuffer is always Landscape(like the iPhone's Home button is at right side), no matter if you capture a video with portrait way or not.
So we need to add good orientation information to the image:
extension CIImage {
func orientationCorrectedImage() -> UIImage? {
var imageOrientation = UIImageOrientation.up
switch UIApplication.shared.statusBarOrientation {
case UIInterfaceOrientation.portrait:
imageOrientation = UIImageOrientation.right
case UIInterfaceOrientation.landscapeLeft:
imageOrientation = UIImageOrientation.down
case UIInterfaceOrientation.landscapeRight:
imageOrientation = UIImageOrientation.up
case UIInterfaceOrientation.portraitUpsideDown:
imageOrientation = UIImageOrientation.left
default:
break;
}
var w = self.extent.size.width
var h = self.extent.size.height
if imageOrientation == .left || imageOrientation == .right || imageOrientation == .leftMirrored || imageOrientation == .rightMirrored {
swap(&w, &h)
}
UIGraphicsBeginImageContext(CGSize(width: w, height: h));
UIImage.init(ciImage: self, scale: 1.0, orientation: imageOrientation).draw(in: CGRect(x: 0, y: 0, width: w, height: h))
let uiImage:UIImage? = UIGraphicsGetImageFromCurrentImageContext()
UIGraphicsEndImageContext();
return uiImage
}
}
Then use it with your code:
private func convert(buffer: CVImageBuffer) -> UIImage? {
let ciImage: CIImage = CIImage(cvPixelBuffer: buffer)
return ciImage.orientationCorrectedImage()
}