blocks|key|1486186|text|您可以使用CIColorControls并设置对比度键kCIInputContrastKey来增加黑白对比度，如下所示：|type|unstyled|depth|inlineStyleRanges|offset|length|style|CODE|entityRanges|data|1486187|Xcode+9·Swift+4|BOLD|1486188|extension+String+{
++++static+let+colorControls+=+"CIColorControls"
}|code-block|syntax|javascript|1486189|extension+UIImage+{
++++var+coreImage:+CIImage?+{+return+CIImage(image:+self)+}
}|1486190|extension+CIImage+{
++++var+uiImage:+UIImage?+{+return+UIImage(ciImage:+self)+}
++++func+applying(contrast+value:+NSNumber)+->+CIImage?+{
++++++++return+applyingFilter(.colorControls,+parameters:+[kCIInputContrastKey:+value])
++++}
++++func+renderedImage()+->+UIImage?+{
++++++++guard+let+image+=+uiImage+else+{+return+nil+}
++++++++return+UIGraphicsImageRenderer(size:+image.size,
+++++++++++++++++++++++++++++++++++++++format:+image.imageRendererFormat).image+{+_+in
++++++++++++image.draw(in:+CGRect(origin:+.zero,+size:+image.size))
++++++++}
++++}
}|1486191|let+url+=+URL(string:+"https://i.stack.imgur.com/Xs4RX.jpg")!
do+{
++++if+let+coreImage+=+UIImage(data:+try+Data(contentsOf:+url))?.coreImage,
++++++++let+increasedContrast+=+coreImage.applying(contrast:+1.5)+{
++++++++imageView.image+=+increasedContrast.uiImage
++++++++//+if+you+need+to+convert+your+image+to+data+(JPEG/PNG)+you+would+need+to+render+the+ciimage+using+renderedImage+method+on+CIImage+++
++++}
}+catch+{
++++print(error)
}|1486192|要将颜色转换为灰度，可以将饱和键kCIInputSaturationKey设置为零：|1486193|extension+CIImage+{
++++func+applying(saturation+value:+NSNumber)+->+CIImage?+{
++++++++return+applyingFilter(.colorControls,+parameters:+[kCIInputSaturationKey:+value])
++++}
++++var+grayscale:+CIImage?+{+return+applying(saturation:+0)+}
}|1486194|let+url+=+URL(string:+"https://i.stack.imgur.com/Xs4RX.jpg")!
do+{
++++if+let+coreImage+=+UIImage(data:+try+Data(contentsOf:+url))?.coreImage,+
++++++++let+grayscale+=+coreImage.grayscale+{
++++++++//+use++grayscale+image+here
++++++++imageView.image+=+grayscale.uiImage
++++}
}+catch+{+
++++print(error)+
}|1486195|entityMap^0|R|J|0|0|F|0|0|0|0|0|G|L|0|0|0^^$0|@$1|2|3|4|5|6|7|11|8|@$9|12|A|13|B|C]]|D|@]|E|$]]|$1|F|3|G|5|6|7|14|8|@$9|15|A|16|B|H]]|D|@]|E|$]]|$1|I|3|J|5|K|7|17|8|@]|D|@]|E|$L|M]]|$1|N|3|O|5|K|7|18|8|@]|D|@]|E|$L|M]]|$1|P|3|Q|5|K|7|19|8|@]|D|@]|E|$L|M]]|$1|R|3|S|5|K|7|1A|8|@]|D|@]|E|$L|M]]|$1|T|3|U|5|6|7|1B|8|@$9|1C|A|1D|B|C]]|D|@]|E|$]]|$1|V|3|W|5|K|7|1E|8|@]|D|@]|E|$L|M]]|$1|X|3|Y|5|K|7|1F|8|@]|D|@]|E|$L|M]]|$1|Z|3|-4|5|6|7|1G|8|@]|D|@]|E|$]]]|10|$]]

You can use CIColorControls and set Contrast Key <code>kCIInputContrastKey</code> to increase the black/white contrast as follow:

Xcode 9 • Swift 4

<pre><code>extension String {
 static let colorControls = "CIColorControls"
}
</code></pre>

<hr>

<pre><code>extension UIImage {
 var coreImage: CIImage? { return CIImage(image: self) }
}
</code></pre>

<hr>

<pre><code>extension CIImage {
 var uiImage: UIImage? { return UIImage(ciImage: self) }
 func applying(contrast value: NSNumber) -&gt; CIImage? {
 return applyingFilter(.colorControls, parameters: [kCIInputContrastKey: value])
 }
 func renderedImage() -&gt; UIImage? {
 guard let image = uiImage else { return nil }
 return UIGraphicsImageRenderer(size: image.size,
 format: image.imageRendererFormat).image { _ in
 image.draw(in: CGRect(origin: .zero, size: image.size))
 }
 }
}
</code></pre>

<hr>

<pre><code>let url = URL(string: "https://i.stack.imgur.com/Xs4RX.jpg")!
do {
 if let coreImage = UIImage(data: try Data(contentsOf: url))?.coreImage,
 let increasedContrast = coreImage.applying(contrast: 1.5) {
 imageView.image = increasedContrast.uiImage
 // if you need to convert your image to data (JPEG/PNG) you would need to render the ciimage using renderedImage method on CIImage 
 }
} catch {
 print(error)
}
</code></pre>

<hr>

To convert from colors to grayscale you can set the Saturation Key <code>kCIInputSaturationKey</code> to zero:

<pre><code>extension CIImage {
 func applying(saturation value: NSNumber) -&gt; CIImage? {
 return applyingFilter(.colorControls, parameters: [kCIInputSaturationKey: value])
 }
 var grayscale: CIImage? { return applying(saturation: 0) }
}
</code></pre>

<hr>

<pre><code>let url = URL(string: "https://i.stack.imgur.com/Xs4RX.jpg")!
do {
 if let coreImage = UIImage(data: try Data(contentsOf: url))?.coreImage, 
 let grayscale = coreImage.grayscale {
 // use grayscale image here
 imageView.image = grayscale.uiImage
 }
} catch { 
 print(error) 
}
</code></pre>

blocks|key|314161|text|去饱和会将你的图像转换成灰度。|type|ordered-list-item|depth|inlineStyleRanges|entityRanges|data|314162|增加对比会把那些灰色推向极端，即黑白。|314163|你可以CIColorControls|unstyled|offset|length|style|CODE|314164|let+ciImage+=+CIImage(image:+image)!
let+blackAndWhiteImage+=+ciImage.applyingFilter("CIColorControls",+withInputParameters:+["inputSaturation":+0,+"inputContrast":+5])|code-block|syntax|javascript|314165|原件：|314166|​|314167|📷|atomic|314168|314169|使用inputContrast+=+1+(默认)：|314170|314171|314172|314173|用inputContrast+=+5|314174|314175|314176|314177|entityMap|0|IMAGE|mutability|IMMUTABLE|imageUrl|https://developer.qcloudimg.com/http-save/yehe-900000/63347fba37863beb385ec0312503573b.png|imageAlt|1|https://developer.qcloudimg.com/http-save/yehe-900000/e6c7b13103c5dbddb4a43b9007721e36.png|2|https://developer.qcloudimg.com/http-save/yehe-900000/cf81490c536c4c49d91a5f0bd7683488.png^0|0|0|3|F|0|0|0|0|0|1|0|0|0|2|H|0|0|0|1|1|0|0|1|H|0|0|0|1|2|0|0^^$0|@$1|2|3|4|5|6|7|1K|8|@]|9|@]|A|$]]|$1|B|3|C|5|6|7|1L|8|@]|9|@]|A|$]]|$1|D|3|E|5|F|7|1M|8|@$G|1N|H|1O|I|J]]|9|@]|A|$]]|$1|K|3|L|5|M|7|1P|8|@]|9|@]|A|$N|O]]|$1|P|3|Q|5|F|7|1Q|8|@]|9|@]|A|$]]|$1|R|3|S|5|F|7|1R|8|@]|9|@]|A|$]]|$1|T|3|U|5|V|7|1S|8|@]|9|@$G|1T|H|1U|1|1V]]|A|$]]|$1|W|3|S|5|F|7|1W|8|@]|9|@]|A|$]]|$1|X|3|Y|5|F|7|1X|8|@$G|1Y|H|1Z|I|J]]|9|@]|A|$]]|$1|Z|3|S|5|F|7|20|8|@]|9|@]|A|$]]|$1|10|3|U|5|V|7|21|8|@]|9|@$G|22|H|23|1|24]]|A|$]]|$1|11|3|S|5|F|7|25|8|@]|9|@]|A|$]]|$1|12|3|13|5|F|7|26|8|@$G|27|H|28|I|J]]|9|@]|A|$]]|$1|14|3|S|5|F|7|29|8|@]|9|@]|A|$]]|$1|15|3|U|5|V|7|2A|8|@]|9|@$G|2B|H|2C|1|2D]]|A|$]]|$1|16|3|S|5|F|7|2E|8|@]|9|@]|A|$]]|$1|17|3|-4|5|F|7|2F|8|@]|9|@]|A|$]]]|18|$19|$5|1A|1B|1C|A|$1D|1E|1F|-4]]|1G|$5|1A|1B|1C|A|$1D|1H|1F|-4]]|1I|$5|1A|1B|1C|A|$1D|1J|1F|-4]]]]

<ol>
<li>Desaturate will convert your image to grayscale</li>
<li>Increasing the contrast will push those grays out to the extremes, i.e. black and white.</li>
</ol>

You can <code>CIColorControls</code>:

<pre><code>let ciImage = CIImage(image: image)!
let blackAndWhiteImage = ciImage.applyingFilter("CIColorControls", withInputParameters: ["inputSaturation": 0, "inputContrast": 5])
</code></pre>

Original:

<a href="https://i.stack.imgur.com/ktoKk.png" rel="noreferrer"><img src="https://i.stack.imgur.com/ktoKk.png" alt="Original"></a>

With <code>inputContrast = 1</code> (default):

<a href="https://i.stack.imgur.com/qI5d7.png" rel="noreferrer"><img src="https://i.stack.imgur.com/qI5d7.png" alt="inputContrast = 1"></a>

With <code>inputContrast = 5</code>:

<a href="https://i.stack.imgur.com/OOvko.png" rel="noreferrer"><img src="https://i.stack.imgur.com/OOvko.png" alt="inputContrast = 5"></a>

blocks|key|1488110|text|在SWIFT5.1中，我为OSX编写了一个扩展方法，它也可以转换到和从NSImage中转换。它利用饱和度和输入对比度来转换图像。我为黑色和白色抽象了一种功能。|type|unstyled|depth|inlineStyleRanges|entityRanges|data|1488111|extension+NSImage+{

++++func+blackAndWhite+()+->+NSImage?
++++{
++++++++return+applying(saturation:+0,inputContrast:+5,image:+self)
++++}

++++func+applying(saturation+value:+NSNumber,+inputContrast+inputContrastValue:+NSNumber,+image:NSImage)+->+NSImage?+{

++++++++let+ciImage+=+CIImage(data:+image.tiffRepresentation!)!
++++++++let+blackAndWhiteImage+=+ciImage.applyingFilter("CIColorControls",+parameters:+["inputSaturation":+value,+"inputContrast":+inputContrastValue])
++++++++let+rep:+NSCIImageRep+=+NSCIImageRep(ciImage:+blackAndWhiteImage)
++++++++let+nsImage:+NSImage+=+NSImage(size:+rep.size)
++++++++nsImage.addRepresentation(rep)

++++++++return+nsImage
++++}

}|code-block|syntax|javascript|1488112|entityMap^0|0|0^^$0|@$1|2|3|4|5|6|7|I|8|@]|9|@]|A|$]]|$1|B|3|C|5|D|7|J|8|@]|9|@]|A|$E|F]]|$1|G|3|-4|5|6|7|K|8|@]|9|@]|A|$]]]|H|$]]

In Swift 5.1 I have written an extension method for OSX which also converts to and from NSImage. It uses saturation and input contrast to convert the image. I have abstracted a func for black and white.

<pre><code>extension NSImage {

 func blackAndWhite () -&gt; NSImage?
 {
 return applying(saturation: 0,inputContrast: 5,image: self)
 }

 func applying(saturation value: NSNumber, inputContrast inputContrastValue: NSNumber, image:NSImage) -&gt; NSImage? {

 let ciImage = CIImage(data: image.tiffRepresentation!)!
 let blackAndWhiteImage = ciImage.applyingFilter("CIColorControls", parameters: ["inputSaturation": value, "inputContrast": inputContrastValue])
 let rep: NSCIImageRep = NSCIImageRep(ciImage: blackAndWhiteImage)
 let nsImage: NSImage = NSImage(size: rep.size)
 nsImage.addRepresentation(rep)

 return nsImage
 }

}

</code></pre>

I am building a scanner component for an iOS app so far I have the result image cropped and in the correct perspective.
Now I need to turn the color image into Black and white "Scanned" document.

I tried to use - "CIPhotoEffectNoir" but it more grayscale then totally black and white. I wish to get a full contrast image with 100% black and 100% white.

How can I achieve that?
Thanks

How can I convert an UIImage to grayscale in Swift using CIFilter?

翻译质量差，导致语言生硬或混乱。

没有提供实际的解决方法或示例。

解答不清晰，无法理解或解决问题。

页面排版不美观，阅读体验差。

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到目前为止，我正在为一个iOS应用程序构建一个扫描仪组件，我已经裁剪了结果图像，并在正确的视角下。现在我需要把彩色图像变成黑白“扫描”文档。我试着使用- "CIPhotoEffectNoir“，但它比完全黑白更灰阶。我希望得到一个100%黑色和100%白色的全对比度图像。我怎样才能做到这一点？谢谢

问如何使用UIImage在Swift中使用CIFilter将CIFilter转换为灰度？
EN

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问如何使用UIImage在Swift中使用CIFilter将CIFilter转换为灰度？EN