什么是最好的核心图像过滤器生产黑白效果？什么是最好的核心图像过滤器生产黑白效果？(What is t

我使用核心图片，并想以产生所选择的图像上的黑色和白色的效果。

我非常希望能够获得相同的排序上可用的Photoshop即红色，青色，绿色，蓝色和品红色的选项。我们的目标是创建不同类型的黑白效果。

有谁知道什么过滤器将是最好的处理这些种类的选择？如果不是没有人知道一个很好的方法来创建使用其他过滤器的黑白效果的？

谢谢

奥利弗

Answer 1:

- (UIImage *)imageBlackAndWhite
{
    CIImage *beginImage = [CIImage imageWithCGImage:self.CGImage];

    CIImage *blackAndWhite = [CIFilter filterWithName:@"CIColorControls" keysAndValues:kCIInputImageKey, beginImage, @"inputBrightness", [NSNumber numberWithFloat:0.0], @"inputContrast", [NSNumber numberWithFloat:1.1], @"inputSaturation", [NSNumber numberWithFloat:0.0], nil].outputImage;
    CIImage *output = [CIFilter filterWithName:@"CIExposureAdjust" keysAndValues:kCIInputImageKey, blackAndWhite, @"inputEV", [NSNumber numberWithFloat:0.7], nil].outputImage; 

    CIContext *context = [CIContext contextWithOptions:nil];
    CGImageRef cgiimage = [context createCGImage:output fromRect:output.extent];
    //UIImage *newImage = [UIImage imageWithCGImage:cgiimage];
    UIImage *newImage = [UIImage imageWithCGImage:cgiimage scale:image.scale orientation:image.imageOrientation];
    CGImageRelease(cgiimage);

    return newImage;
}

UPD：对于iOS6有CIColorMonochrome过滤器，但我打了它，发现它并不像我那么好。

Answer 2:

我这里是用CIColorMonochrome

- (UIImage *)imageBlackAndWhite
{
    CIImage *beginImage = [CIImage imageWithCGImage:self.CGImage];

    CIImage *output = [CIFilter filterWithName:@"CIColorMonochrome" keysAndValues:kCIInputImageKey, beginImage, @"inputIntensity", [NSNumber numberWithFloat:1.0], @"inputColor", [[CIColor alloc] initWithColor:[UIColor whiteColor]], nil].outputImage;

    CIContext *context = [CIContext contextWithOptions:nil];
    CGImageRef cgiimage = [context createCGImage:output fromRect:output.extent];
    UIImage *newImage = [UIImage imageWithCGImage:cgiimage scale:self.scale orientation:self.imageOrientation];

    CGImageRelease(cgiimage);

    return newImage;
}

Answer 3:

创建一个纯单色效果，我使用CIColorMatrix与R，G和B向量参数都设置为（0.2125，0.7154，0.0721，0），并留下它们的默认值α和偏置矢量。

该值是RGB到灰度转换系数我抬头对在某一时刻的互联网络。通过改变这些系数，就可以改变输入通道的贡献。通过缩放矢量的每一个副本，以及任选地设定偏置向量，可以colourize输出。

Answer 4:

这里是转换为夫特（iOS的7及以上）的顶部额定溶液：

func blackAndWhiteImage(image: UIImage) -> UIImage {
    let context = CIContext(options: nil)
    let ciImage = CoreImage.CIImage(image: image)!

    // Set image color to b/w
    let bwFilter = CIFilter(name: "CIColorControls")!
    bwFilter.setValuesForKeysWithDictionary([kCIInputImageKey:ciImage, kCIInputBrightnessKey:NSNumber(float: 0.0), kCIInputContrastKey:NSNumber(float: 1.1), kCIInputSaturationKey:NSNumber(float: 0.0)])
    let bwFilterOutput = (bwFilter.outputImage)!

    // Adjust exposure
    let exposureFilter = CIFilter(name: "CIExposureAdjust")!
    exposureFilter.setValuesForKeysWithDictionary([kCIInputImageKey:bwFilterOutput, kCIInputEVKey:NSNumber(float: 0.7)])
    let exposureFilterOutput = (exposureFilter.outputImage)!

    // Create UIImage from context
    let bwCGIImage = context.createCGImage(exposureFilterOutput, fromRect: ciImage.extent)
    let resultImage = UIImage(CGImage: bwCGIImage, scale: 1.0, orientation: image.imageOrientation)

    return resultImage
}

Answer 5:

至于答案建议使用CIColorMonochrome ：现在有从iOS7一些专用灰度滤镜（和OS X 10.9）：

CIPhotoEffectTonal
模仿黑与白的摄影胶片没有显著改变对比度。
CIPhotoEffectNoir：
模仿黑与白的摄影胶片以夸张的对比度

来源： https://developer.apple.com/library/mac/documentation/GraphicsImaging/Reference/CoreImageFilterReference/index.html

Answer 6:

下面是从@Shmidt最喜欢的答案写成UIImage的扩展与斯威夫特性能更新：

import CoreImage

extension UIImage
{
    func imageBlackAndWhite() -> UIImage?
    {
        if let beginImage = CoreImage.CIImage(image: self)
        {
            let paramsColor: [String : AnyObject] = [kCIInputBrightnessKey: NSNumber(double: 0.0),
                                                     kCIInputContrastKey:   NSNumber(double: 1.1),
                                                     kCIInputSaturationKey: NSNumber(double: 0.0)]
            let blackAndWhite = beginImage.imageByApplyingFilter("CIColorControls", withInputParameters: paramsColor)

            let paramsExposure: [String : AnyObject] = [kCIInputEVKey: NSNumber(double: 0.7)]
            let output = blackAndWhite.imageByApplyingFilter("CIExposureAdjust", withInputParameters: paramsExposure)

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

Answer 7:

MACOS（NSImage中）斯威夫特3版@ FBente的转换@ Shmidt的回答的：

extension NSImage
{
    func imageBlackAndWhite() -> NSImage?
    {
        if let cgImage = self.cgImage(forProposedRect: nil, context: nil, hints: nil)
        {
            let beginImage = CIImage.init(cgImage: cgImage)
            let paramsColor: [String : AnyObject] = [kCIInputBrightnessKey: NSNumber(value: 0.0),
                                                     kCIInputContrastKey:   NSNumber(value: 1.1),
                                                     kCIInputSaturationKey: NSNumber(value: 0.0)]
            let blackAndWhite = beginImage.applyingFilter("CIColorControls", withInputParameters: paramsColor)

            let paramsExposure: [String : AnyObject] = [kCIInputEVKey: NSNumber(value: 0.7)]
            let output = blackAndWhite.applyingFilter("CIExposureAdjust", withInputParameters: paramsExposure)

            if let processedCGImage = CIContext().createCGImage(output, from: output.extent) {
                return NSImage(cgImage: processedCGImage, size: self.size)
            }
        }
        return nil
    }
}

Answer 8:

我曾尝试Shmidt解决方案，但它似乎对我来说太过度曝光的iPad Pro的。我使用的只是他的解决方案的第一部分，而不会暴露过滤器：

- (UIImage *)imageBlackAndWhite
{
    CIImage *beginImage = [CIImage imageWithCGImage:self.CGImage];

    CIImage *blackAndWhite = [CIFilter filterWithName:@"CIColorControls" keysAndValues:kCIInputImageKey, beginImage, @"inputBrightness", [NSNumber numberWithFloat:0.0], @"inputContrast", [NSNumber numberWithFloat:1.1], @"inputSaturation", [NSNumber numberWithFloat:0.0], nil].outputImage;
    CIImage *output = [blackAndWhite valueForKey:@"outputImate"]; 

    CIContext *context = [CIContext contextWithOptions:nil];
    CGImageRef cgiimage = [context createCGImage:output fromRect:output.extent];
    //UIImage *newImage = [UIImage imageWithCGImage:cgiimage];
    UIImage *newImage = [UIImage imageWithCGImage:cgiimage scale:image.scale orientation:image.imageOrientation];
    CGImageRelease(cgiimage);

    return newImage;
}

文章来源: What is the best Core Image filter to produce black and white effects?