How to Change Brightness, Contrast and Saturation Using Cicolorcontrols via Uislider with Swift

How to change Brightness, Contrast and Saturation using CIColorControls via UISlider with Swift

You problem is that every time you slide the slider you are applying the filter to the resulting image of the previous filter instead of applying it to the original image. Btw you can make your filter a lot more responsive when sliding the UISlider if you just create a CGImage once the user is finished. Your code should look like this:

let displayinPercentage = Int((sender.value/200) * 10000)
brightnessValueLabel.text = String(displayinPercentage)
let beginImage = CIImage(image: originalImage)
filter.setValue(beginImage, forKey: kCIInputImageKey)
filter.setValue(sender.value, forKey: kCIInputBrightnessKey)
if let ciimage = filter.outputImage {
    filteredImage = ciimage
    selectedPictureImageView.image = UIImage(ciImage: filteredImage)
}

How to change Brightness and Contrast with one UISlider with Swift

As you have to keep reference and track for both filter key-value and apply both key filters at the same time while slider value changes.

Here is the demo code.

Note: As this is just a demo I used force unwrapping. You need to handle nil value.

class ViewController: UIViewController {
    
    @IBOutlet weak var imageToFilter: UIImageView!
    
    public var brightness : Float = 0.0
    public var contrast : Float = 1.0
    
    var filter: CIFilter? = CIFilter(name: "CIColorControls")
    var originalImage = UIImage(named: "image_name")
    
    override func viewDidLoad() {
        super.viewDidLoad()
    }
    
    func applyImageFilter(for image: UIImage) -> UIImage? {
        
        guard let sourceImage = CIImage(image: image),
              let filter = self.filter else { return nil }
        
        filter.setValue(sourceImage, forKey: kCIInputImageKey)
        
        filter.setValue(self.contrast, forKey: kCIInputContrastKey)
        filter.setValue(self.brightness, forKey: kCIInputBrightnessKey)
        
        
        guard let output = filter.outputImage else { return nil }
        
        guard let outputCGImage = CIContext().createCGImage(output, from: output.extent) else { return nil }
        
        let filteredImage = UIImage(cgImage: outputCGImage, scale: image.scale, orientation: image.imageOrientation)
        
        return filteredImage
    }
    
    @IBAction func sliderValueChangeAction(_ sender: UISlider) {
        if sender.tag == 0 {
            self.brightness = sender.value
        
        } else if sender.tag == 1 {
            self.contrast = sender.value
        }
        
        imageToFilter.image = self.applyImageFilter(for: originalImage!)
    }
}

CIColorControls wrong brightness

The "Brightness" slider in Photos is not mapped to the "traditional" brightness value (that is used in CIColorControls). Apple uses more sophisticated algorithms under the hood that, among others, take the image's content into account. I'm afraid there's no single core image filter that can reproduce that result. But it looks like Photos also increased the contrast when reducing the brightness, so you could try that.

Is there a setting for CIColorControls that leaves an image unaffected?

These are the values that should return the original image

kCIInputSaturationKey: 1.0
kCIInputBrightnessKey: 0.0
kCIInputContrastKey: 1.0

Brightness, saturation and contrast with ColorMatrix in Swift

The colorMatrix property is nil because you never initialized it properly.

Delete dynamic var colorMatrix: CIFilter? from your controller and use the code below.

class editionViewController: UIViewController {

    @IBOutlet weak var editionImageView: UIImageView!

    override func viewDidLoad() {
        super.viewDidLoad()

        if let image = UIImage(named: "myImage.png") {
            editionImageView.image = image.liaFilter()
        }
    }
}

extension UIImage {
    //Lia filter
    func liaFilter() -> UIImage {
        let inImage = CIImage(image: self)

        let rgbVector = CIVector(x: 0, y: 1, z: 0, w: 0)
        let aVector = CIVector(x: 0, y: 0, z: 0, w: 1)

        dynamic let colorMatrix = CIFilter(name: "CIColorMatrix")

        if colorMatrix != nil {
            colorMatrix?.setDefaults()
            colorMatrix?.setValue(inImage, forKey: kCIInputImageKey)
            colorMatrix?.setValue(rgbVector, forKey: "inputRVector")
            colorMatrix?.setValue(rgbVector, forKey: "inputGVector")
            colorMatrix?.setValue(rgbVector, forKey: "inputBVector")
            colorMatrix?.setValue(aVector, forKey: "inputAVector")

            if let output = colorMatrix?.outputImage, let cgImage = CIContext().createCGImage(output, from: output.extent) {
                return UIImage(cgImage: cgImage)
            }
        }

        return self
    }
}

I fixed your UIImage extension method.

I put the initializer for CIFilter in the Extension method so you don't have to hold a reference for it.

Hope this help.

How to adjust brightness and contrast of CGImageRef

You want Core Image. The filter for your purpose is CIColorControls.

Change filter intensity like brightness from 0 to 100 via slider control in gpuimage2 swift

Every time your slider value changes, you're creating a new ContrastAdjustment filter instance and attaching it to the picture. Your old filter instance is still there, and the RenderView will ignore any inputs beyond the first one that goes into it. In fact, you should have been seeing warnings on the console telling you about that fact that you're adding too many inputs to the RenderView.

Instead of creating a whole new ContrastAdjustment filter each time, simply save your contrast filter as an instance variable and adjust its contrast property when the slider changes.

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