ios - 如何对一张图片应用滤镜？

Question

我是 Swift 的初学者，我制作了一个应用程序“照片编辑器”。我有个问题。我需要对一张图片应用一些滤镜。我有四个 slider (棕褐色、对比度、亮度、饱和度)和一张图像。我想将所有这些过滤器应用于我的图像。

我试图改变我的代码逻辑，但我有同样的问题

@objc func sliderValueDidChange(sender: UISlider!) 

    if sender.tag == 0 {
            let originalCIImage = CIImage(image: self.image!)
            let value = sender.value
            self.sepiaLabelValue.text = String(Int(value*100))
            if  let sepiaCIImage = sepiaFilter(originalCIImage!, intensity: Double(value)) {
                filteredImage = sepiaCIImage
                self.imageView.image = UIImage(ciImage: sepiaCIImage)
            }

        } else if sender.tag == 1 {
            let originalCIImage = CIImage(image: self.image!)
            let value = sender.value
            self.brightnessValue.text = String(Int(value*100))
            if let brightnessCIImage = brightnessFilter(originalCIImage!, intensity: Double(value)) {
                filteredImage = brightnessCIImage
                self.imageView.image = UIImage(ciImage:brightnessCIImage)
            }

        } else if sender.tag == 2 {
            let originalCIImage = CIImage(image: self.image!)
            let value = sender.value
            self.contrastLabel.text = String(Int(value*100))
            let contrastCIImage = contrastFilter(originalCIImage!, intensity: Double(value))
            self.imageView.image = UIImage(ciImage:contrastCIImage!)

        } else if sender.tag == 3 {
            let originalCIImage = CIImage(image: self.image!)
            let value = sender.value
            self.saturationValue.text = String(Int(value*100))
            let saturationCIImage = saturationFilter(originalCIImage!, intensity: Double(value))
            self.imageView.image = UIImage(ciImage:saturationCIImage!)
        }
}


func sepiaFilter(_ input: CIImage, intensity: Double) -> CIImage?
    {
        let sepiaFilter = CIFilter(name:"CISepiaTone")
        sepiaFilter?.setValue(input, forKey: kCIInputImageKey)
        sepiaFilter?.setValue(intensity, forKey: kCIInputIntensityKey)
        return sepiaFilter?.outputImage
    }

    func brightnessFilter(_ input: CIImage, intensity: Double) -> CIImage? {
        let brightnessFilter = CIFilter(name: "CIColorControls")
        brightnessFilter?.setValue(input, forKey: kCIInputImageKey)
        brightnessFilter?.setValue(intensity, forKey: kCIInputBrightnessKey)
        return brightnessFilter?.outputImage
    }

    func contrastFilter(_ input: CIImage, intensity: Double) -> CIImage? {
        let contrastFilter = CIFilter(name: "CIColorControls")
        contrastFilter?.setValue(input, forKey: kCIInputImageKey)
        contrastFilter?.setValue(intensity, forKey: kCIInputContrastKey)
        return contrastFilter?.outputImage
    }

    func saturationFilter(_ input: CIImage, intensity: Double) -> CIImage? {
        let saturationFilter = CIFilter(name: "CIColorControls")
        saturationFilter?.setValue(input, forKey: kCIInputImageKey)
        saturationFilter?.setValue(intensity, forKey: kCIInputSaturationKey)
        return saturationFilter?.outputImage
    }

当我应用第一个过滤器然后应用下一个过滤器时，第一个过滤器的值被确定为开始状态。如何将所有滤镜应用到我的图像？

Answer 1

正如 Gigi 所说，诀窍是在值发生变化时始终对图像应用两个滤镜。这应该可以解决问题:

let colorControlsFilter = CIFilter(name: "CIColorControls")!
let sepiaFilter = CIFilter(name:"CISepiaTone")!


@objc func sliderValueDidChange(sender: UISlider!) {
    switch sender.tag {
    case 0: 
        let value = sender.value
        self.sepiaLabelValue.text = String(Int(value*100))
        self.sepiaFilter.setValue(value, forKey: kCIInputIntensityKey)
    case 1:
        let value = sender.value
        self.brightnessValue.text = String(Int(value*100))
        self.colorControlsFilter.setValue(value, forKey: kCIInputBrightnessKey)
    case 2:
        let value = sender.value
        self.contrastLabel.text = String(Int(value*100))
        self.colorControlsFilter.setValue(value, forKey: kCIInputContrastKey)
    case 3:
        let value = sender.value
        self.saturationValue.text = String(Int(value*100))
        self.colorControlsFilter.setValue(value, forKey: kCIInputSaturationKey)
    default: pass
    }

    self.updateImage()
}

func updateImage() {
    let originalCIImage = CIImage(image: self.image!)
    // first apply color controls (contrast, brightness, saturation), then sepia
    self.colorControlsFilter.setValue(originalCIImage, forKey: kCIInputImageKey)
    self.sepiaFilter.setValue(self.colorControlsFilter.outputImage, forKey: kCIInputImageKey)
    self.imageView.image = UIImage(ciImage: self.sepiaFilter.outputImage!)
}