Objective C: CIFilter 返回 nil 图像

Question

我正在编写一个函数，它将滤镜应用于图像和 return 新图像。我写了下面的代码：

+ (UIImage*)applyFilter:(UIImage*) photo {
    CIImage *image = [[CIImage alloc] initWithCGImage:photo.CGImage];
    CIFilter *filter = [CIFilter filterWithName:@"CIphotoEffectTransfer"
                                  keysAndValues: kCIInputImageKey, image,
                        @"inputIntensity", @0.8, nil];
    CIImage *outputImage = [filter outputImage];

    UIImage* newPhoto = [self imageFromCIImage:outputImage];
    return newPhoto;
}

我运行遇到的问题是该函数 return 是一张零照片，而不是应用滤镜的照片。有趣的是，如果我将过滤器名称更改为 @"CIVignetteEffect" 它将起作用。我不明白为什么一个过滤器有效而另一个过滤器无效。我从以下 link 中找到了两个过滤器：https://developer.apple.com/library/tvos/documentation/GraphicsImaging/Reference/CoreImageFilterReference/index.html#//apple_ref/doc/filter/ci/CIPhotoEffectTransfer

Answer 1

我认为滤镜的正确名称是 CIPhotoEffectTransfer，而不是 CIphotoeffectTransfer。

试试这个代码...我过去用它来过滤照片，所以我知道它有效：

+ (UIImage*)applyFilter:(UIImage*) photo {
UIImageOrientation orientation = photo.imageOrientation;
CIImage* image = [CIImage imageWithCGImage:photo.CGImage];
CIContext *context = [CIContext contextWithOptions:nil];
CIFilter *filter = [CIFilter filterWithName:@"CIPhotoEffectTransfer"];
[filter setValue:image forKey:kCIInputImageKey];
CIImage *outputImage = [filter outputImage];
CGImageRef cgimg = [context createCGImage:outputImage fromRect:[outputImage extent]];
UIImage *newPhoto = [UIImage imageWithCGImage:cgimg scale:1.0 orientation:orientation];
CGImageRelease(cgimg);
context = nil;
return newPhoto;

}

Answer 2

试试这个，

我们实现了CIFilter效果，

       //CIVignette Effect 

        CIContext *imageContext = [CIContext contextWithOptions:nil];
        CIImage *image = [[CIImage alloc] initWithImage:inputimage];

        CIFilter *vignette = [CIFilter filterWithName:@"CIVignette"];
        [vignette setDefaults];
        [vignette setValue: image forKey: @"inputImage"];
        [vignette setValue: [NSNumber numberWithFloat: 1.0] forKey: @"inputIntensity"];
        [vignette setValue: [NSNumber numberWithFloat: 10.00 ] forKey: @"inputRadius"];
         CIImage *result = [vignette valueForKey: @"outputImage"];
        CGImageRef cgImageRef = [imageContext createCGImage:result fromRect:[result extent]];
        UIImage *targetImage = [UIImage imageWithCGImage:cgImageRef];

多重效果的详细实现可以参考这个GitHub工程文件ImageFilter

希望这个回答对某些人有所帮助。

Objective C: CIFilter 返回 nil 图像

Objective C: CIFilter returning nil image

ios

objective-c

core-image

cifilter