产生黑白效果的最佳 Core Image 滤镜是什么? [英] What is the best Core Image filter to produce black and white effects?

问题描述

我正在使用 Core Image，并希望在所选图像上产生黑白效果.

理想情况下，我希望能够访问 Photoshop 上可用的相同类型的选项，即红色、青色、绿色、蓝色和洋红色.目标是创建不同类型的黑白效果.

有谁知道什么过滤器最适合操纵这些选项?如果没有，有人知道使用其他滤镜创建黑白效果的好方法吗?

谢谢

奥利弗

解决方案

- (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.scaleorientation:image.imageOrientation];CGImageRelease(cgiimage);返回新图像；}

更新: iOS6 有 CIColorMonochrome 过滤器，但我玩了一下，发现它不如我的.p>

I am using Core Image and would like to produce a black and white effect on the chosen image.

Ideally I would like to have access to the same sort of options that are available on Photoshop i.e. Reds, Cyan, Greens, Blues and Magenta. The goal being to create different types of the black and white effect.

Does anyone know what filter would be best to manipulate these sort of options? If not does anyone know of a good approach to creating the black and white effect using other filters?

Thanks

Oliver

解决方案

- (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.: For iOS6 there is CIColorMonochrome filter, but I played with it and found it not so good as mine.

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