我正在制作照片编辑应用程序.
当用户选择照片时,使用以下代码将其自动转换为黑白照片：
func blackWhiteImage(image: UIImage) -> Data {
print("Starting black & white")
let orgImg = CIImage(image: image)
let bnwImg = orgImg?.applyingFilter("CIColorControls",withInputParameters: [kCIInputSaturationKey:0.0])
let outputimage = UIImage(ciImage: bnwImg!)
print("Black & white complete")
return UIImagePNGRepresentation(outputimage)!
}
我对此代码的问题是我不断收到此错误：
Fatal error: unexpectedly found nil while unwrapping an Optional value
我的代码略有不同,但是当它到达UIImagePNG / JPEGRepresentation(xx)部分时它仍然会中断.
有没有办法从CIImage中获取PNG或JPEG数据,以便在图像视图/ UIImage中使用？
任何其他方法都没有详细说明应该使用哪些代码.
只需开始一个新的图形上下文并在那里绘制灰度图像：
func blackWhiteImage(image: UIImage) -> Data? {
guard let ciImage = CIImage(image: image)?.applyingFilter("CIColorControls",withInputParameters: [kCIInputSaturationKey:0.0]) else { return nil }
UIGraphicsBeginImageContextWithOptions(image.size,false,image.scale)
defer { UIGraphicsEndImageContext() }
UIImage(ciImage: ciImage).draw(in: CGRect(origin: .zero,size: image.size))
guard let redraw = UIGraphicsGetimageFromCurrentimageContext() else { return nil }
return UIImagePNGRepresentation(redraw)
}
您还可以扩展UIImage以返回灰度图像：
extension UIImage {
var grayscale: UIImage? {
guard let ciImage = CIImage(image: self)?.applyingFilter("CIColorControls",withInputParameters: [kCIInputSaturationKey: 0]) else { return nil }
UIGraphicsBeginImageContextWithOptions(size,scale)
defer { UIGraphicsEndImageContext() }
UIImage(ciImage: ciImage).draw(in: CGRect(origin: .zero,size: size))
return UIGraphicsGetimageFromCurrentimageContext()
}
}
let profilePicture = UIImage(data: try! Data(contentsOf: URL(string:"http://i.stack.imgur.com/Xs4RX.jpg")!))!
if let grayscale = profilePicture.grayscale,let data = UIImagePNGRepresentation(grayscale) {
print(data.count) // 689035
}