关于可可触摸：如何将UIImage转换为CIImage，反之亦然

How to Convert UIImage to CIImage and vice versa

我正在尝试从屏幕上显示的ImageView中获取CIImage。

1	UIImage *image = myImageView.image;

将图像UIImage转换为CIImage。

1	CIImage *cImage = [....];

如何执行此操作？

1 2	CIImage ciImage = [UIImage imageNamed:@"test.png"].CIImage; UIImage uiImage = [[UIImage alloc] initWithCIImage:ciImage];

要修复myUIImage.CIImage返回nil(如[UIImageView image])的情况，您可以改为执行[CIImage imageWithCGImage:myUIImage.CGImage] – Dylan Hand

快速版本：

1 2	let ciImage = UIImage(named:"test.png")!.ciImage let uiImage = UIImage(ciImage: ciImage)

要修复myUIImage.CIImage返回nil的情况，可以改为执行CIImage(cgImage: myUIImage!.cgImage!)。

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虽然王长兴的回答实际上是正确的，但苹果表示UIImage.CIImage并不总是有效。具体来说，来自PocketCoreImage：

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// 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];

Apple还使用以下内容，这些内容对我不起作用：

1	[UIImage imageWithCIImage:_filteredImage]

根据这篇文章改编的我的个人实现确实对我有用：

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// 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]];

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这是最兼容的方式：

1 2	UIImage* u =[UIImage imageNamed:@"image.png"]; CIImage* ciimage = [[CIImage alloc] initWithCGImage:u.CGImage];

现在使用ciimage ...

和Swift版本：

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

(if let语句中的固定错字)

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这是我在项目中使用过的完整代码示例。

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- (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。如果尝试直接从CIImage转换为UIImage，将会遇到问题。例如，调用

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

将返回nil。

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

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

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迅速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

changx答案的快速示例：

1 2	guard let ciimage = CIImage(image: uiimage) else { return } let image = UIImage(CIImage: ciimage)

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将UIImage转换为CIImage时，我有2种单独的情况，有时有时是零，有时不是。下面的代码解决了它：

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