This calss-level UIImage extension aims to help identifying raw value for UIImageOrientation. This may be useful when warking with CGImage or CIImage classes. Swift 3

UIImage+TiffOrientationFix.swift

extension UIImage {
    class func imageOrientationToTiffOrientation(_ value: UIImageOrientation) -> Int32 {
        switch (value) {
        case .up:
            return 1
        case .down:
            return 3
        case .left:
            return 8
        case .right:
            return 6
        case .upMirrored:
            return 2
        case .downMirrored:
            return 4
        case .leftMirrored:
            return 5
        case .rightMirrored:
            return 7
        }
    }

}