ios - 如何使用 CIDetector 和 Swift 在图像中裁剪检测到的矩形

Question

我正在开发一个检测身份证的应用程序，我正在尝试使用 ios 内置的 CIDetector 来检测实时预览中的矩形对象。我在这里使用本教程中解释的解决方案 CoreImage Detectors

我得到了流动的结果 图像

我的问题：有没有办法提取和裁剪检测到的矩形？

Answer 1

func cropBusinessCardForPoints(image: CIImage, topLeft: CGPoint, topRight: CGPoint, bottomLeft: CGPoint, bottomRight: CGPoint) -> CIImage {

    var businessCard: CIImage
    businessCard = image.imageByApplyingFilter(
        "CIPerspectiveTransformWithExtent",
        withInputParameters: [
            "inputExtent": CIVector(CGRect: image.extent),
            "inputTopLeft": CIVector(CGPoint: topLeft),
            "inputTopRight": CIVector(CGPoint: topRight),
            "inputBottomLeft": CIVector(CGPoint: bottomLeft),
            "inputBottomRight": CIVector(CGPoint: bottomRight)])
    businessCard = image.imageByCroppingToRect(businessCard.extent)

    return businessCard
}

Answer 2

Swift 3，简单的解决方案

让 faceScanningArea = CGRect(x: 0, y: 0, width: 50, height: 50)

theFaceFrame.image = UIImage(cgImage(orginalImage.image?.cgImage)!.cropping(to: faceScanningArea)!)