使用 CGColorSpaceCreateDeviceGray() 将彩色 UIImage 转换为灰度

Question

我正在尝试将 UIImage 转换为 GrayScale。它所做的只是一个黑色图像。

func convertToGrayScale2(image: UIImage) -> UIImage {
    let imageRect:CGRect = CGRect(x:0, y:0, width:image.size.width, height: image.size.height)
    let colorSpace = CGColorSpaceCreateDeviceGray()
    let width = image.size.width
    let height = image.size.height

    let bitmapInfo = CGBitmapInfo(rawValue: CGImageAlphaInfo.none.rawValue)
    let context = CGContext(data: nil, width: Int(width), height: Int(height), bitsPerComponent: 8, bytesPerRow: 0, space: colorSpace, bitmapInfo: bitmapInfo.rawValue)
    let imageRef = context!.makeImage()
    context?.draw(imageRef!, in: imageRect)
    let newImage = UIImage(cgImage: imageRef!)

    return newImage
}

代码有问题吗？我需要现有代码的帮助。它以前工作过。突然它不工作了。

Answer 1

一种可能的替代方法是使用 CoreImage 过滤器。请参考以下 and its 。希望能帮助到你。编码愉快！

Answer 2

您可以改用这个函数：

func convertImageToDifferentColorScale(with originalImage:UIImage, imageStyle:String) -> UIImage {
    let currentFilter = CIFilter(name: imageStyle)
    currentFilter!.setValue(CIImage(image: originalImage), forKey: kCIInputImageKey)
    let output = currentFilter!.outputImage
    let context = CIContext(options: nil)
    let cgimg = context.createCGImage(output!,from: output!.extent)
    let processedImage = UIImage(cgImage: cgimg!)
    return processedImage
}

下面是您如何使用的示例：

 let newImage = convertImageToDifferentColorScale(with: UIImage(named: "0318_1")!, imageStyle: "CIPhotoEffectNoir")
 testingImageView.image = newImage

在imageStyle部分，有如下几种不同的风格：

 CIColorCrossPolynomial
 CIColorCube
 CIColorCubeWithColorSpace
 CIColorInvert
 CIColorMap
 CIColorMonochrome
 CIColorPosterize
 CIFalseColor
 CIMaskToAlpha
 CIMaximumComponent
 CIMinimumComponent
 CIPhotoEffectChrome
 CIPhotoEffectFade
 CIPhotoEffectInstant
 CIPhotoEffectMono
 CIPhotoEffectNoir

而'CIPhotoEffectNoir'是一个可以给你gray scale的选择。

Answer 3

func convertToGrayScale(image: UIImage) -> UIImage {
        let imageRect:CGRect = CGRect(x:0, y:0, width:image.size.width, height: image.size.height)
        let colorSpace = CGColorSpaceCreateDeviceGray()
        let width = image.size.width
        let height = image.size.height

        let bitmapInfo = CGBitmapInfo(rawValue: CGImageAlphaInfo.none.rawValue)
        let context = CGContext(data: nil, width: Int(width), height: Int(height), bitsPerComponent: 8, bytesPerRow: 0, space: colorSpace, bitmapInfo: bitmapInfo.rawValue)
        //have to draw before create image

        context?.draw(image.cgImage!, in: imageRect)
        let imageRef = context!.makeImage()
        let newImage = UIImage(cgImage: imageRef!)

        return newImage
    }

使用 CGColorSpaceCreateDeviceGray() 将彩色 UIImage 转换为灰度

Convert UIImage colored to grayscale using CGColorSpaceCreateDeviceGray()

image

grayscale

ios

swift