如何通过 UISlider 和 Swift 使用 CIColorControls 更改亮度、对比度和饱和度

Question

我正在开发一款照片滤镜应用，如您所见，我添加了一项功能来调整对比度、亮度、饱和度和噪点。但问题是它们独立工作，这意味着当我调整亮度时，当我开始编辑对比度时，它会恢复到原始亮度。

这是我将亮度设置为最大（图像变白）然后尝试调整其对比度并且滑块改变原始图像的对比度时的预览。

在这里，我能够捕捉到释放滑块并将其值放在原始图像上的时刻，正如您所看到的那样，它可以工作，在演示中，我将饱和度设置为 0，然后将同一饱和度图片的对比度更改为 0 .

。

问题是，现在当我单击滑块而不更改其值时，它会使当前值加倍。例如，如果我将亮度 5 和饱和度 10 并决定在单击亮度后立即调整亮度，它的值会增加一倍，我不知道为什么。 这是一个例子。我只是单击滑块而不更改其值。

这是代码

  @objc func sliderValueDidChange(_ sender: UISlider!) {

    if sender.tag == 0 {

        let displayinPercentage: Int = Int((sender.value/200) * 10000)
        brightnessValueLabel.text = ("\(displayinPercentage)")
        selectedPictureImageView.image = originalImage
        let beginImage = CIImage(image: selectedPictureImageView.image!)
        self.filter = CIFilter(name: "CIColorControls")
        self.filter?.setValue(beginImage, forKey: kCIInputImageKey)
        self.filter.setValue(sender.value, forKey: kCIInputBrightnessKey)
        self.filteredImage = self.filter?.outputImage
        selectedPictureImageView.image = UIImage(cgImage: self.context.createCGImage(self.filteredImage!, from: (self.filteredImage?.extent)!)!)
        sliderValue = sender.value


    } else if sender.tag == 1 {

        let displayinPercentage: Int = Int((sender.value/200) * 10000)
        contrastValueLabel.text = ("\(displayinPercentage)")
        self.selectedPictureImageView.image = originalImage
        let beginImage = CIImage(image: self.selectedPictureImageView.image!)
        self.filter = CIFilter(name: "CIColorControls")
        self.filter?.setValue(beginImage, forKey: kCIInputImageKey)
        self.filter.setValue(sender.value, forKey: kCIInputContrastKey)
        self.filteredImage = self.filter?.outputImage
        self.selectedPictureImageView.image = UIImage(cgImage: self.context.createCGImage(self.filteredImage!, from: (self.filteredImage?.extent)!)!)
        sliderValue = sender.value

    } else if sender.tag == 2 {

        let displayinPercentage: Int = Int((sender.value/200) * 10000)
        saturationValueLabel.text = ("\(displayinPercentage)")
        self.selectedPictureImageView.image = originalImage
        let beginImage = CIImage(image: self.selectedPictureImageView.image!)
        self.filter = CIFilter(name: "CIColorControls")
        self.filter?.setValue(beginImage, forKey: kCIInputImageKey)
        self.filter.setValue(sender.value, forKey: kCIInputSaturationKey)
        self.filteredImage = self.filter?.outputImage
        self.selectedPictureImageView.image = UIImage(cgImage: self.context.createCGImage(self.filteredImage!, from: (self.filteredImage?.extent)!)!)
        sliderValue = sender.value

    } else if sender.tag == 3 {

        let displayinPercentage: Int = Int((sender.value/200) * 10000)
        sharpenValueLabel.text = ("\(displayinPercentage)")
        self.selectedPictureImageView.image = originalImage
        let beginImage = CIImage(image: self.selectedPictureImageView.image!)
        self.filter = CIFilter(name: "CIUnsharpMask")
        self.filter?.setValue(beginImage, forKey: kCIInputImageKey)
        self.filter.setValue(7, forKey: kCIInputRadiusKey)
        self.filter.setValue(sender.value, forKey: kCIInputIntensityKey)
        self.filteredImage = self.filter?.outputImage
        self.selectedPictureImageView.image = UIImage(cgImage: self.context.createCGImage(self.filteredImage!, from: (self.filteredImage?.extent)!)!)
        sliderValue = sender.value

    }
}

@objc func sliderValueDidEnd(_ sender: UISlider!) {

    if sender.tag == 0 {
        originalImage = selectedPictureImageView.image
        sender.value = sliderValue
        print("Unpressed button slider value is \(sender.value)")
    } else if sender.tag == 1 {
        originalImage = selectedPictureImageView.image
        sender.value = sliderValue
        print("Unpressed button slider value is \(sender.value)")
    } else if sender.tag == 2 {
        originalImage = selectedPictureImageView.image
        sender.value = sliderValue
        print("Unpressed button slider value is \(sender.value)")
    } else if sender.tag == 3 {
        originalImage = selectedPictureImageView.image
        sender.value = sliderValue
        print("Unpressed button slider value is \(sender.value)")
    }
}

我认为一切正常，我只是对过滤器值进行了错误的计算。

Answer 1

您的问题是，每次滑动滑块时，您都会将过滤器应用于前一个过滤器的结果图像，而不是将其应用于原始图像。顺便说一句，如果您只是在用户完成后创建一个 CGImage ，那么您可以在滑动 UISlider 时使您的过滤器更具响应性。您的代码应如下所示：

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)
}