CIImage-UIImage-Orientation-Fix

Demo of UIImageOrientation to TIFF Orientation conversion that fixes orientation issues when creating CIImage from UIImage

If you are creating a CIImage from a UIImage which originates from the photo library (e.g. with UIImagePickerController) you may find the simple conversion such as CIImage(image: UIImage(named: "sunflower.jpg")!) fails to orient images properly, for example portrait images will be rotated to landscape.

This issue can be resolved by looking at the imageOrientation of the UIImage returned by the system, translating it from a UIImageOrientation to a TIFF orientation and applying that to the CIImage.

The code to do that looks like this (where image is the supplied UIImage):

let ciImage = CIImage(image: image)?.imageByApplyingOrientation(imageOrientationToTiffOrientation(image.imageOrientation))

The conversion function, imageOrientationToTiffOrientation, is a simple switch:

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
    }
}

There’s a demonstration project available here at my GitHub repository here that implements this fix.