Increase/decrease brightness of image using UISlider? - ios

Question

I am building an iOS app which is based on image operations.
I want to increase and decrease brightness of image by slider value.
I have used this code to do this:
#IBOutlet var imageView: UIImageView!
#IBOutlet var uiSlider : UISlider!
override func viewDidLoad()
{
super.viewDidLoad()
var image = UIImage(named: "54715869.jpg")
imageView.image = image
uiSlider.minimumValue = -0.2
uiSlider.maximumValue = 0.2
uiSlider.value = 0.0
uiSlider.maximumTrackTintColor = UIColor(red: 0.1, green: 0.7, blue: 0, alpha: 1)
uiSlider.minimumTrackTintColor = UIColor.blackColor()
uiSlider.addTarget(self, action: "brightnesssliderMove:", forControlEvents: UIControlEvents.TouchUpInside)
uiSlider.addTarget(self, action: "brightnesssliderMove:", forControlEvents: UIControlEvents.TouchUpOutside)
}
func brightnesssliderMove(sender: UISlider)
{
var filter = CIFilter(name: "CIColorControls");
filter.setValue(NSNumber(float: sender.value), forKey: "inputBrightness")
var image = self.imageView.image
var rawimgData = CIImage(image: image)
filter.setValue(rawimgData, forKey: "inputImage")
var outpuImage = filter.valueForKey("outputImage")
imageView.image = UIImage(CIImage: outpuImage as CIImage)
}
Now my question is that when I increase slider value it also increase brightness of image but only when I change slider position for first time.
When I am again changing the position of slider I am getting this errror:
fatal error: unexpectedly found nil while unwrapping an Optional value.
This error is coming at line:
imageView.image = UIImage(CIImage: outpuImage as CIImage)
This time rawimgData data comes nil.

Answer 1

I found answer to my question here is how i have done coding.
import CoreImage
class ViewController: UIViewController,UIImagePickerControllerDelegate,UINavigationControllerDelegate {
var aCIImage = CIImage();
var contrastFilter: CIFilter!;
var brightnessFilter: CIFilter!;
var context = CIContext();
var outputImage = CIImage();
var newUIImage = UIImage();
override func viewDidLoad() {
super.viewDidLoad()
var aUIImage = imageView.image;
var aCGImage = aUIImage?.CGImage;
aCIImage = CIImage(CGImage: aCGImage)
context = CIContext(options: nil);
contrastFilter = CIFilter(name: "CIColorControls");
contrastFilter.setValue(aCIImage, forKey: "inputImage")
brightnessFilter = CIFilter(name: "CIColorControls");
brightnessFilter.setValue(aCIImage, forKey: "inputImage")
}
func sliderContrastValueChanged(sender: UISlider) {
contrastFilter.setValue(NSNumber(float: sender.value), forKey: "inputContrast")
outputImage = contrastFilter.outputImage;
var cgimg = context.createCGImage(outputImage, fromRect: outputImage.extent())
newUIImage = UIImage(CGImage: cgimg)!
imageView.image = newUIImage;
}
func sliderValueChanged(sender: UISlider) {
brightnessFilter.setValue(NSNumber(float: sender.value), forKey: "inputBrightness");
outputImage = brightnessFilter.outputImage;
let imageRef = context.createCGImage(outputImage, fromRect: outputImage.extent())
newUIImage = UIImage(CGImage: imageRef)!
imageView.image = newUIImage;
}
}

Answer 2

You can use AlamofireImage, here's an example of how you can do it:
#IBAction func brightnessChanged(sender: UISlider) {
let filterParameters = ["inputBrightness": sender.value]
imageView.image = originalImage.af_imageWithAppliedCoreImageFilter("CIColorControls", filterParameters: filterParameters)
}