CIColorMatrix 过滤器结果很奇怪

Question

我正在尝试创建一个 CIFilter 来转换以下 QR 码：

收件人：

这是我正在使用的代码：

let invert = CIFilter(name: "CIColorInvert")
invert!.setDefaults()
invert!.setValue(ciImage, forKey: "inputImage")

let filter = CIFilter(name: "CIColorMatrix")
filter?.setDefaults()
filter?.setValue(invert?.outputImage, forKey: kCIInputImageKey)

let r = CGFloat(70.0/255.0)
let g = CGFloat(224.0/255.0)
let b = CGFloat(182.0/255.0)

filter?.setValue(CIVector(x: r, y: 0, z: 0, w: 0), forKey: "inputRVector")
filter?.setValue(CIVector(x: 0, y: g, z: 0, w: 0), forKey: "inputGVector")
filter?.setValue(CIVector(x: 0, y: 0, z: b, w: 0), forKey: "inputBVector")
filter?.setValue(CIVector(x: 0, y: 0, z: 0, w: 1), forKey: "inputAVector")

代码所做的是首先反转正常的 QR 码，使其成为白底黑字，然后获取该图像并对其应用滤镜。代码的结果是这样的：

这不是我想要的颜色。如果有任何帮助，我将不胜感激！

谢谢！

Answer 1

您可以使用以下方法之一来实现 QR filter effect 使用 coreImage。

输出：

方法一：Using Custom Filter

Step1: 为您的 custom kernel 创建单独的 class，如下所示。

class CustomFilter: CIFilter {
var inputImage: CIImage?

override public var outputImage: CIImage! {
    get {
        if let inputImage = self.inputImage {
            let args = [inputImage as AnyObject]
            return createCustomKernel().apply(withExtent: inputImage.extent, arguments: args)
        } else {
            return nil
        }
      }
    }
 }


func createCustomKernel() -> CIColorKernel {
let kernelString =
    "kernel vec4 chromaKey( __sample s) { \n" +
        "  vec4 newPixel = s.rgba;" +
        "  newPixel[0] = 0.0;" +
        "  newPixel[2] = newPixel[2] / 2.0;" +
        "  return newPixel;\n" +
"}"
return CIColorKernel(string: kernelString)!
 }

在您的 ViewController 中，您可以如下声明自定义过滤器。

 var context = CIContext(options: nil)

 func customQRFilter() {

    let myInvertFilter = CIFilter(name: "CIColorInvert")
    myInvertFilter!.setValue(CIImage(image: imageView.image!), forKey: kCIInputImageKey)
    let output = myInvertFilter!.outputImage 

    let filter = CustomFilter()
    filter.setValue(output, forKey: kCIInputImageKey)
    
    // Get the filtered output image and return it
    let outputImage = filter.outputImage!
    let cgimg = context.createCGImage(outputImage,from: output!.extent)
    let processedImage = UIImage(cgImage: cgimg!)
    imageView.image = processedImage
   }

方法 2： 使用 CIColorMatrix 过滤器。

    func colorMatrixFilter() {
    
    let myInvertFilter = CIFilter(name: "CIColorInvert")
    myInvertFilter!.setValue(CIImage(image: imageView.image!), forKey: kCIInputImageKey)
    let output = myInvertFilter!.outputImage 
    
    let filter = CIFilter(name: "CIColorMatrix")
    filter?.setDefaults()
    filter?.setValue(output, forKey: kCIInputImageKey)
    
    let r = CGFloat(0.0)
    let g = CGFloat(0.9)
    let b = CGFloat(0.416)
    
    filter?.setValue(CIVector(x: r, y: 0, z: 0, w: 0), forKey: "inputRVector")
    filter?.setValue(CIVector(x: 0, y: g, z: 0, w: 0), forKey: "inputGVector")
    filter?.setValue(CIVector(x: 0, y: 0, z: b, w: 0), forKey: "inputBVector")
    filter?.setValue(CIVector(x: 0, y: 0, z: 0, w: 1), forKey: "inputAVector")
    
    let outputs = filter?.outputImage 
    let cgimg = context.createCGImage(outputs!,from: output!.extent)
    let processedImage = UIImage(cgImage: cgimg!)
    imageView2.image = processedImage
}

注意：我建议你用colour Picker tool选择你想要的RGB value of any colour。

Answer 2

我必须创建一个上下文没有颜色空间，以获得正确的颜色：

...
let ciContext = CIContext(options: [CIContextOption.outputColorSpace: NSNull(), CIContextOption.workingColorSpace: NSNull()])
let cgimg = ciContext.createCGImage(outputs!,from: output!.extent)
let processedImage = UIImage(cgImage: cgimg!)

(Swift 4)

CIColorMatrix 过滤器结果很奇怪

CIColorMatrix Filter result is weird

ios

swift

image-processing

core-image