CODEWITHSUNDEEP
iosswiftciimagecifacefeaturefacial-identification
Anters Bear
Anters Bear

Reputation: 1956

Converting CIImage coordinates to CGRect from CIFaceFeature

I am trying to place a square rectangle over a user's face which I am recognizing using CIFaceFeature in real time over a full screen (self.view.frame) video feed. However, the coordinates I am getting from CIFaceFeature.bounds are from a different coordinate system than that used by views. I have tried converting these coordinates from this and other examples. But since I don't I am running this atop a video feed I don't have an image I can pass into CIImage to ease with the conversion of coordinates. Below is an example of my configuration, any idea how I can convert to a usable CGRect?

func captureOutput(_ output: AVCaptureOutput, didOutput sampleBuffer: CMSampleBuffer, from connection: AVCaptureConnection) {

    let imageBuffer = CMSampleBufferGetImageBuffer(sampleBuffer)
    let opaqueBuffer = Unmanaged<CVImageBuffer>.passUnretained(imageBuffer!).toOpaque()
    let pixelBuffer = Unmanaged<CVPixelBuffer>.fromOpaque(opaqueBuffer).takeUnretainedValue()
    let sourceImage = CIImage(cvPixelBuffer: pixelBuffer)
    let features = self.faceDetector!.features(in: sourceImage, options: options)

    if (features.count != 0) {
        let faceImage = sourceImage
        let faceDetector = CIDetector(ofType: CIDetectorTypeFace, context: nil, options: [CIDetectorAccuracy: CIDetectorAccuracyHigh])
        let faces = faceDetector?.features(in: faceImage) as! [CIFaceFeature]

        let transformScale = CGAffineTransform(scaleX: 1, y: -1)
        let transform = transformScale.translatedBy(x: 0, y: -faceImage.extent.height)
        for feature in features as! [CIFaceFeature] {

            faceBounds = feature.bounds

            var fb = faceBounds?.applying(transform)
            // imageViewSize is the screen frame
            let scale = min(imageViewSize.width / fb!.width,
                            imageViewSize.height / fb!.height)

            let dx = (imageViewSize.width - fb!.width * scale) / 2
            let dy = (imageViewSize.height - fb!.height * scale) / 2

            fb?.applying(CGAffineTransform(scaleX: scale, y: scale))
            fb?.origin.x += dx
            fb?.origin.y += dy

            realFaceRect = fb // COMPLETELY WRONG :'(
    }
}

Upvotes: 0

Views: 768

Answers (1)

Anters Bear
Anters Bear

Reputation: 1956

If anyone runs into the same problem. Here's an easy solution

let imgHeight = CGFloat(CVPixelBufferGetHeight(pixelBuffer))
let ratio = self.view.frame.width / self.visage!.imgHeight

func convertFrame(frame: CGRect, ratio: CGFloat) -> CGRect {
    let x = frame.origin.y * ratio
    let y = frame.origin.x * ratio
    let width = frame.height * ratio
    let height = frame.width * ratio
    return CGRect(x: x, y: y, width: width, height: height)
}

func convertPoint(point: CGPoint, ratio: CGFloat) -> CGPoint {
    let x = point.y * ratio
    let y = point.x * ratio
    return CGPoint(x: x, y: y)
}

Upvotes: 0

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