如何使用 Swift 中的滑块值更改 kCIInputBrightnessKey，无论滑块获得什么值，我都会得到白色或黑色图片

Question

滑块的最小值为-1，最大值为+1。

    @IBAction func changeContrast(_ sender: UISlider) {

    DispatchQueue.main.async {
        let beginImage = CIImage(image: self.myImageView.image!)
        self.filter = CIFilter(name: "CIColorControls")
        self.filter?.setValue(beginImage, forKey: kCIInputImageKey)
        self.filter.setValue(sender.value, forKey: kCIInputBrightnessKey)
        print("Current value of the slider - \(sender.value)")
        self.filteredImage = self.filter?.outputImage
        self.myImageView.image = UIImage(cgImage: self.context.createCGImage(self.filteredImage!, from: (self.filteredImage?.extent)!)!)
    }
}

这也是滑块值的打印输出。

Current value of the slider - 0.228814
Current value of the slider - 0.271186
Current value of the slider - 0.322034
Current value of the slider - 0.38983
Current value of the slider - 0.45339
Current value of the slider - 0.525424
Current value of the slider - 0.610169
Current value of the slider - 0.682203
Current value of the slider - 0.75
Current value of the slider - 0.79661
Current value of the slider - 0.847458
Current value of the slider - 0.889831
Current value of the slider - 0.915254
Current value of the slider - 0.927966

Answer 1

原因是滤镜每次都在从前一个滑块更改值生成的结果图像中工作，这里是因为这一行

let beginImage = CIImage(image: self.myImageView.image!)

因此您需要通过添加此行来重置 imageView 的图像顶部功能

self.myImageView.image = UIImage(named:"girl")

//

 @IBAction func changeContrast(_ sender: UISlider) {
    self.myImageView.image = UIImage(named:"girl")
    let beginImage = CIImage(image: self.myImageView.image!)
    self.filter = CIFilter(name: "CIColorControls")
    self.filter?.setValue(beginImage, forKey: kCIInputImageKey)
    self.filter.setValue(sender.value, forKey: kCIInputBrightnessKey)
    print("Current value of the slider - \(sender.value)")
    self.filteredImage = self.filter?.outputImage
    self.myImageView.image = UIImage(cgImage: self.context.createCGImage(self.filteredImage!, from: (self.filteredImage?.extent)!)!)
}

此外，最小滑块值应为 0，最大值为 1

如何使用 Swift 中的滑块值更改 kCIInputBrightnessKey，无论滑块获得什么值，我都会得到白色或黑色图片

How change kCIInputBrightnessKey using slider value in Swift, I'm getting either white or black picture whatever value the slider get

ios

swift

image-processing

uislider

core-image