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UIImageに白黒フィルターを適用する

UIImageに白黒フィルターを適用する必要があります。ユーザーが撮った写真が見えるビューがありますが、画像の色を変えるアイデアはありません。

- (void)viewDidLoad {
    [super viewDidLoad];
    self.navigationItem.title = NSLocalizedString(@"#Paint!", nil);
    imageView.image = image;
}

どうやってやるの？

objective-cuiimageciimage
19
user3422862

目的C

- (UIImage *)convertImageToGrayScale:(UIImage *)image {


    // Create image rectangle with current image width/height
    CGRect imageRect = CGRectMake(0, 0, image.size.width, image.size.height);

    // Grayscale color space
    CGColorSpaceRef colorSpace = CGColorSpaceCreateDeviceGray();

    // Create bitmap content with current image size and grayscale colorspace
    CGContextRef context = CGBitmapContextCreate(nil, image.size.width, image.size.height, 8, 0, colorSpace, kCGImageAlphaNone);

    // Draw image into current context, with specified rectangle
    // using previously defined context (with grayscale colorspace)
    CGContextDrawImage(context, imageRect, [image CGImage]);

    // Create bitmap image info from pixel data in current context
    CGImageRef imageRef = CGBitmapContextCreateImage(context);

    // Create a new UIImage object
    UIImage *newImage = [UIImage imageWithCGImage:imageRef];

    // Release colorspace, context and bitmap information
    CGColorSpaceRelease(colorSpace);
    CGContextRelease(context);
    CFRelease(imageRef);

    // Return the new grayscale image
    return newImage; 
}

スウィフト

func convertToGrayScale(image: UIImage) -> UIImage {

    // Create image rectangle with current image width/height
    let imageRect:CGRect = CGRect(x:0, y:0, width:image.size.width, height: image.size.height)

    // Grayscale color space
    let colorSpace = CGColorSpaceCreateDeviceGray()
    let width = image.size.width
    let height = image.size.height

    // Create bitmap content with current image size and grayscale colorspace
    let bitmapInfo = CGBitmapInfo(rawValue: CGImageAlphaInfo.none.rawValue)

    // Draw image into current context, with specified rectangle
    // using previously defined context (with grayscale colorspace)
    let context = CGContext(data: nil, width: Int(width), height: Int(height), bitsPerComponent: 8, bytesPerRow: 0, space: colorSpace, bitmapInfo: bitmapInfo.rawValue)
    context?.draw(image.cgImage!, in: imageRect)
    let imageRef = context!.makeImage()

    // Create a new UIImage object
    let newImage = UIImage(cgImage: imageRef!)

    return newImage
}
27
MCMatan

ciimage タグから判断すると、おそらくOPは、Core Imageがこれを行うための迅速で簡単な方法を提供すると考えていました（正しく）。

これが、ObjCの両方です。

- (UIImage *)grayscaleImage:(UIImage *)image {
    CIImage *ciImage = [[CIImage alloc] initWithImage:image];
    CIImage *grayscale = [ciImage imageByApplyingFilter:@"CIColorControls"
        withInputParameters: @{kCIInputSaturationKey : @0.0}];
    return [UIImage imageWithCIImage:grayscale];
}

とスウィフト：

func grayscaleImage(image: UIImage) -> UIImage {
    let ciImage = CIImage(image: image)
    let grayscale = ciImage.imageByApplyingFilter("CIColorControls",
        withInputParameters: [ kCIInputSaturationKey: 0.0 ])
    return UIImage(CIImage: grayscale)
}

CIColorControls は、イメージをグレースケールに変換できる組み込みのコアイメージフィルターの1つにすぎません。 CIPhotoEffectMono 、 CIPhotoEffectNoir 、および CIPhotoEffectTonal は異なるトーンマッピングプリセットであり（それぞれパラメーターを使用しません）、フィルターを使用して独自のトーンマッピングを実行できます CIColorMap のように。

独自のCGBitmapContextを作成して描画する方法とは異なり、これらは追加の作業なしで元の画像のサイズ/スケールとアルファを保持します。

25
rickster

PiratMのソリューションは機能しますが、アルファチャネルは失われます。アルファチャネルを保持するには、いくつかの追加手順を実行する必要があります。

+(UIImage *)convertImageToGrayScale:(UIImage *)image {
    // Create image rectangle with current image width/height
    CGRect imageRect = CGRectMake(0, 0, image.size.width, image.size.height);

    // Grayscale color space
    CGColorSpaceRef colorSpace = CGColorSpaceCreateDeviceGray();

    // Create bitmap content with current image size and grayscale colorspace
    CGContextRef context = CGBitmapContextCreate(nil, image.size.width, image.size.height, 8, 0, colorSpace, kCGImageAlphaNone);

    // Draw image into current context, with specified rectangle
    // using previously defined context (with grayscale colorspace)
    CGContextDrawImage(context, imageRect, [image CGImage]);

    // Create bitmap image info from pixel data in current context
    CGImageRef imageRef = CGBitmapContextCreateImage(context);

    // Release colorspace, context and bitmap information
    CGColorSpaceRelease(colorSpace);
    CGContextRelease(context);

    context = CGBitmapContextCreate(nil,image.size.width, image.size.height, 8, 0, nil, kCGImageAlphaOnly );
    CGContextDrawImage(context, imageRect, [image CGImage]);
    CGImageRef mask = CGBitmapContextCreateImage(context);

    // Create a new UIImage object
    UIImage *newImage = [UIImage imageWithCGImage:CGImageCreateWithMask(imageRef, mask)];
    CGImageRelease(imageRef);
    CGImageRelease(mask);

    // Return the new grayscale image
    return newImage;
}
19
Chris Stillwell

@ricksterのバージョンは、アルファチャネルを考慮すると適切に見えます。ただし、.AspectFitまたはFill contentModeのないUIImageViewはそれを表示できません。したがって、UIImageはCGImageで作成する必要があります。 Swift UIImage拡張機能として実装されたこのバージョンは、現在のスケールを保持し、いくつかのオプションの入力パラメーターを提供します。

import CoreImage

extension UIImage
{
    /// Applies grayscale with CIColorControls by settings saturation to 0.0.
    /// - Parameter brightness: Default is 0.0.
    /// - Parameter contrast: Default is 1.0.
    /// - Returns: The grayscale image of self if available.
    func grayscaleImage(brightness: Double = 0.0, contrast: Double = 1.0) -> UIImage?
    {
        if let ciImage = CoreImage.CIImage(image: self, options: nil)
        {
            let paramsColor: [String : AnyObject] = [ kCIInputBrightnessKey: NSNumber(double: brightness),
                                                      kCIInputContrastKey:   NSNumber(double: contrast),
                                                      kCIInputSaturationKey: NSNumber(double: 0.0) ]
            let grayscale = ciImage.imageByApplyingFilter("CIColorControls", withInputParameters: paramsColor)

            let processedCGImage = CIContext().createCGImage(grayscale, fromRect: grayscale.extent)
            return UIImage(CGImage: processedCGImage, scale: self.scale, orientation: self.imageOrientation)
        }
        return nil
    }
}

より長くより速い方法は、@ ChrisStillwells回答の修正版です。 Swiftのアルファチャネルと現在のスケールを考慮したUIImage拡張機能として実装されます。

extension UIImage
{
    /// Create a grayscale image with alpha channel. Is 5 times faster than grayscaleImage().
    /// - Returns: The grayscale image of self if available.
    func convertToGrayScale() -> UIImage?
    {
        // Create image rectangle with current image width/height * scale
        let pixelSize = CGSize(width: self.size.width * self.scale, height: self.size.height * self.scale)
        let imageRect = CGRect(Origin: CGPointZero, size: pixelSize)
        // Grayscale color space
        if let colorSpace: CGColorSpaceRef = CGColorSpaceCreateDeviceGray()
        {
            // Create bitmap content with current image size and grayscale colorspace
            let bitmapInfo = CGBitmapInfo(rawValue: CGImageAlphaInfo.None.rawValue)
            if let context: CGContextRef = CGBitmapContextCreate(nil, Int(pixelSize.width), Int(pixelSize.height), 8, 0, colorSpace, bitmapInfo.rawValue)
            {
                // Draw image into current context, with specified rectangle
                // using previously defined context (with grayscale colorspace)
                CGContextDrawImage(context, imageRect, self.CGImage)
                // Create bitmap image info from pixel data in current context
                if let imageRef: CGImageRef = CGBitmapContextCreateImage(context)
                {
                    let bitmapInfoAlphaOnly = CGBitmapInfo(rawValue: CGImageAlphaInfo.Only.rawValue)
                    if let contextAlpha = CGBitmapContextCreate(nil, Int(pixelSize.width), Int(pixelSize.height), 8, 0, nil, bitmapInfoAlphaOnly.rawValue)
                    {
                        CGContextDrawImage(contextAlpha, imageRect, self.CGImage)
                        if let mask: CGImageRef = CGBitmapContextCreateImage(contextAlpha)
                        {
                            // Create a new UIImage object
                            if let newCGImage = CGImageCreateWithMask(imageRef, mask)
                            {
                                // Return the new grayscale image
                                return UIImage(CGImage: newCGImage, scale: self.scale, orientation: self.imageOrientation)
                            }
                        }
                    }
                }
            }

        }
        // A required variable was unexpected nil
        return nil
    }
}
6
FBente

Swift 3.0バージョン：

extension UIImage {
    func convertedToGrayImage() -> UIImage? {
        let width = self.size.width
        let height = self.size.height
        let rect = CGRect(x: 0.0, y: 0.0, width: width, height: height)
        let colorSpace = CGColorSpaceCreateDeviceGray()
        let bitmapInfo = CGBitmapInfo(rawValue: CGImageAlphaInfo.none.rawValue)

        guard let context = CGContext(data: nil, width: Int(width), height: Int(height), bitsPerComponent: 8, bytesPerRow: 0, space: colorSpace, bitmapInfo: bitmapInfo.rawValue) else {
            return nil
        }
        guard let cgImage = cgImage else { return nil }

        context.draw(cgImage, in: rect)
        guard let imageRef = context.makeImage() else { return nil }
        let newImage = UIImage(cgImage: imageRef.copy()!)

        return newImage
    }
}
1
Anson Yao

Swift3 + GPUImage

import GPUImage

extension UIImage {
    func blackWhite() -> UIImage? {
        guard let image: GPUImagePicture = GPUImagePicture(image: self) else {
            print("unable to create GPUImagePicture")
            return nil
        }
        let filter = GPUImageAverageLuminanceThresholdFilter()
        image.addTarget(filter)
        filter.useNextFrameForImageCapture()
        image.processImage()
        guard let processedImage: UIImage = filter.imageFromCurrentFramebuffer(with: UIImageOrientation.up) else {
            print("unable to obtain UIImage from filter")
            return nil
        }
        return processedImage
    }
}
1
neoneye

Swift 4ソリューション

extension UIImage {            
    var withGrayscale: UIImage {    
        guard let ciImage = CIImage(image: self, options: nil) else { return self }    
        let paramsColor: [String: AnyObject] = [kCIInputBrightnessKey: NSNumber(value: 0.0), kCIInputContrastKey: NSNumber(value: 1.0), kCIInputSaturationKey: NSNumber(value: 0.0)]
        let grayscale = ciImage.applyingFilter("CIColorControls", parameters: paramsColor)    
        guard let processedCGImage = CIContext().createCGImage(grayscale, from: grayscale.extent) else { return self }
        return UIImage(cgImage: processedCGImage, scale: scale, orientation: imageOrientation)
    }
}
1
Charlton Provatas

このコード（Objective C）は機能します：

CIImage * ciimage = ...;
CIFilter * filter = [CIFilter filterWithName:@"CIColorControls" withInputParameters:@{kCIInputSaturationKey : @0.0,kCIInputContrastKey : @10.0,kCIInputImageKey : ciimage}];
CIImage * grayscale  = [filtre outputImage];

kCIInputContrastKey : @10.0は、ほぼ白黒の画像を取得することです。

0
Jo Essfb

Swift 3.0

  func convertImageToGrayScale(image: UIImage) -> UIImage {
    // Create image rectangle with current image width/height
    let imageRect = CGRect(x: 0, y: 0,width: image.size.width, height : image.size.height)
    // Grayscale color space
    let colorSpace = CGColorSpaceCreateDeviceGray()
    // Create bitmap content with current image size and grayscale colorspace
    let context = CGContext(data: nil, width: Int(image.size.width), height: Int(image.size.height), bitsPerComponent: 8, bytesPerRow: 0, space: colorSpace, bitmapInfo: CGImageAlphaInfo.none.rawValue)
    // Draw image into current context, with specified rectangle
    // using previously defined context (with grayscale colorspace)
    context?.draw(image.cgImage!, in: imageRect)

    // Create bitmap image info from pixel data in current context
    let imageRef = context!.makeImage()
    // Create a new UIImage object
    let newImage = UIImage(cgImage: imageRef!)
    // Release colorspace, context and bitmap information
//MARK: ToolBar Button Methods

    // Return the new grayscale image
    return newImage
}
0
pradip kikani

Swift 1.2バージョン

/// convert background image to gray scale
///
/// param: flag if true, image will be rendered in grays scale
func convertBackgroundColorToGrayScale(flag: Bool) {
    if flag == true {
        let imageRect = self.myImage.frame

        let colorSpace = CGColorSpaceCreateDeviceGray()
        let width = imageRect.width
        let height = imageRect.height

        let bitmapInfo = CGBitmapInfo(CGImageAlphaInfo.None.rawValue)
        var context = CGBitmapContextCreate(nil, Int(width), Int(height), 8, 0, colorSpace, bitmapInfo)
        let image = self.musicBackgroundColor.image!.CGImage

        CGContextDrawImage(context, imageRect, image)
        let imageRef = CGBitmapContextCreateImage(context)

        let newImage = UIImage(CGImage: CGImageCreateCopy(imageRef))

        self.myImage.image = newImage
    } else {
        // do something else
    }
}
0
Miralem Cebic

In Swift 5、CoreImageを使用して画像フィルターを実行し、

ありがとう@rickster

extension UIImage{
    var grayscaled: UIImage?{
        let ciImage = CIImage(image: self)
        let grayscale = ciImage?.applyingFilter("CIColorControls",
                                                parameters: [ kCIInputSaturationKey: 0.0 ])
        if let gray = grayscale{
            return UIImage(ciImage: gray)
        }
        else{
            return nil
        }
    }
}
0
dengST30