iOS: When applying a CIFilter to a UIImage the result image is rotated

Question

When i apply CIFilter to a image that is captured from Back camera the result is perfect but When i apply CIFilter to a image that is captured from Front camera the result is not good because image rotated whats wrong there??

My filter function is given below

func ApplyFilter()->UIImage
{
    let ciContext = CIContext(options: nil)
    let coreImage = CIImage(image: myImage!)
    let filter = CIFilter(name: "CIPhotoEffectNoir" )
    filter!.setDefaults()
    filter!.setValue(coreImage, forKey: kCIInputImageKey)
    let filteredImageData = filter!.valueForKey(kCIOutputImageKey) as! CIImage
    let filteredImageRef = ciContext.createCGImage(filteredImageData, fromRect: filteredImageData.extent)
    var newImage = UIImage(CGImage: filteredImageRef);

    return newImage

}

Answer 1

thats because your front camera captures a flipped image just Like a Mirror Does. what you need to do is fix the image Orientation after capturing the image.

Swift 3

extension UIImage {

func fixOrientation() -> UIImage {

    // No-op if the orientation is already correct
    if ( self.imageOrientation == UIImageOrientation.up ) {
        return self;
    }

    // We need to calculate the proper transformation to make the image upright.
    // We do it in 2 steps: Rotate if Left/Right/Down, and then flip if Mirrored.
    var transform: CGAffineTransform = CGAffineTransform.identity

    if ( self.imageOrientation == UIImageOrientation.down || self.imageOrientation == UIImageOrientation.downMirrored ) {
        transform = transform.translatedBy(x: self.size.width, y: self.size.height)
        transform = transform.rotated(by: CGFloat(Double.pi))
    }

    if ( self.imageOrientation == UIImageOrientation.left || self.imageOrientation == UIImageOrientation.leftMirrored ) {
        transform = transform.translatedBy(x: self.size.width, y: 0)
        transform = transform.rotated(by: CGFloat(Double.pi / 2.0))
    }

    if ( self.imageOrientation == UIImageOrientation.right || self.imageOrientation == UIImageOrientation.rightMirrored ) {
        transform = transform.translatedBy(x: 0, y: self.size.height);
        transform = transform.rotated(by: CGFloat(-Double.pi / 2.0));
    }

    if ( self.imageOrientation == UIImageOrientation.upMirrored || self.imageOrientation == UIImageOrientation.downMirrored ) {
        transform = transform.translatedBy(x: self.size.width, y: 0)
        transform = transform.scaledBy(x: -1, y: 1)
    }

    if ( self.imageOrientation == UIImageOrientation.leftMirrored || self.imageOrientation == UIImageOrientation.rightMirrored ) {
        transform = transform.translatedBy(x: self.size.height, y: 0);
        transform = transform.scaledBy(x: -1, y: 1);
    }

    // Now we draw the underlying CGImage into a new context, applying the transform
    // calculated above.
    let ctx: CGContext = CGContext(data: nil, width: Int(self.size.width), height: Int(self.size.height),
                                   bitsPerComponent: self.cgImage!.bitsPerComponent, bytesPerRow: 0,
                                   space: self.cgImage!.colorSpace!,
                                   bitmapInfo: self.cgImage!.bitmapInfo.rawValue)!;

    ctx.concatenate(transform)

    if ( self.imageOrientation == UIImageOrientation.left ||
        self.imageOrientation == UIImageOrientation.leftMirrored ||
        self.imageOrientation == UIImageOrientation.right ||
        self.imageOrientation == UIImageOrientation.rightMirrored ) {
        ctx.draw(self.cgImage!, in: CGRect(x: 0,y: 0,width: self.size.height,height: self.size.width))
    } else {
        ctx.draw(self.cgImage!, in: CGRect(x: 0,y: 0,width: self.size.width,height: self.size.height))
    }

    // And now we just create a new UIImage from the drawing context and return it
    return UIImage(cgImage: ctx.makeImage()!)
}

}

Use It As

let myImage = picCaptured.fixOrientation()

and then apply CIFilter to that Image

Answer 2

Make sure the image size before apply filters means width should be less than height because image/photos taken from front camera have grater width than length that may cause problem after applying filters. https://developer.apple.com/library/content/documentation/DeviceInformation/Reference/iOSDeviceCompatibility/Cameras/Cameras.html