如何将UIImage转换为CIImage，反之亦然

我试图CIImage从屏幕上显示的ImageView获取。

UIImage *image = myImageView.image;

将图像转换UIImage为CIImage。

CIImage *cImage = [....];

这该怎么做？

CIImage *ciImage = [UIImage imageNamed:@"test.png"].CIImage;
UIImage *uiImage = [[UIImage alloc] initWithCIImage:ciImage];

要解决类似这样的myUIImage.CIImage回报问题，您可以改用– Dylan Handnil[UIImageView image][CIImage imageWithCGImage:myUIImage.CGImage]

迅捷版：

let ciImage = UIImage(named: "test.png")!.ciImage
let uiImage = UIImage(ciImage: ciImage)

要解决类似myUIImage.ciImage返回的情况，nil您可以这样做CIImage(cgImage: myUIImage!.cgImage!)。

尽管王长兴的答案实际上是正确的，但苹果公司表示UIImage.CIImage不会一直有效。具体来说，来自PocketCoreImage：

// Create a CIImage from the _inputImage.  While UIImage has a property returning
// a CIImage representation of it, there are cases where it will not work.  This is the
// most compatible route.
_filteredImage = [[CIImage alloc] initWithCGImage:_inputImage.CGImage options:nil];

苹果还使用以下内容，但对我不起作用：

[UIImage imageWithCIImage:_filteredImage] 

从这篇文章改编的我的个人实现确实对我有用：

// result is a CIImage, output of my filtering.  
// returnImage is (obviously) a UIImage that I'm going to return.
CIContext *context = [CIContext contextWithOptions:nil];
UIImage *returnImage = 
[UIImage imageWithCGImage:[context createCGImage:result fromRect:result.extent]];

这是最兼容的方式：

UIImage* u =[UIImage imageNamed:@"image.png"];
CIImage* ciimage = [[CIImage alloc] initWithCGImage:u.CGImage];

现在使用ciimage ...

和Swift版本：

let i1 = UIImage(named: "testImage")
if let cgi1 = i1?.cgImage {
   let ci = CIImage(cgImage: cgi1)
   //use ci
}

（修复了if let语句中的错字）

这是我在项目中使用的完整代码示例。

- (UIImage *)makeUIImageFromCIImage:(CIImage *)ciImage {
    CIContext *context = [CIContext contextWithOptions:nil];
    CGImageRef cgImage = [context createCGImage:ciImage fromRect:[ciImage extent]];

    UIImage* uiImage = [UIImage imageWithCGImage:cgImage];
    CGImageRelease(cgImage);

    return uiImage;
}

CIImage基本上是图像的配方。如果您尝试直接从转换为CIImage，则会遇到问题UIImage。例如，打电话

NSData * UIImageJPEGRepresentation (
   UIImage *image,
   CGFloat compressionQuality
);

会回来的nil。

func toCIImage(image: UIImage) -> CIImage {
    return image.CIImage ?? CIImage(CGImage: image.CGImage!)
}

func toUIImage(image: CIImage) -> UIImage {
    return UIImage(CIImage: image)
}

changx答案的Swift示例：

guard let ciimage = CIImage(image: uiimage) else { return }
let image = UIImage(CIImage: ciimage)

迅捷3/4

UIImage> CIImage

let ciimage = CIImage(image: image)

https://developer.apple.com/documentation/uikit/uiimage/1624090-init

CIImage> UIImage

let image = UIImage(ciImage: ciimage)

https://developer.apple.com/documentation/coreimage/ciimage/1624119-init

将UIImage转换为CIImage时，我有2种单独的情况，有时有时为零，有时则为零。下面的代码解决了它：

CIImage *ciImage;
ciImage=[[CIImage alloc] initWithImage:imageToConvert];
if (ciImage==nil)
    ciImage=imageToConvert.CIImage;