iOS 6上的CIGaussianBlur和CIAffineClamp [英] CIGaussianBlur and CIAffineClamp on iOS 6

问题描述

我试图在iOS 6上使用CoreImage模糊图像而没有明显的黑色边框。 Apple文档声明使用CIAffineClamp过滤器可以实现此目的，但我无法从过滤器获取输出图像。这是我尝试过的，但不幸的是，当我访问[clampFilter outputImage]时会创建一个空图像。如果我只执行模糊，则会产生图像，但是使用黑色插入边框。

I am trying to blur an image using CoreImage on iOS 6 without having a noticeable black border. Apple documentation states that using a CIAffineClamp filter can achieve this but I'm not able to get an output image from the filter. Here's what I tried, but unfortunately an empty image is created when I access the [clampFilter outputImage]. If I only perform the blur an image is produced, but with the dark inset border.

CIImage *inputImage = [[CIImage alloc] initWithCGImage:self.CGImage];

CIContext *context = [CIContext contextWithOptions:nil];

CGAffineTransform transform = CGAffineTransformIdentity;

CIFilter *clampFilter = [CIFilter filterWithName:@"CIAffineClamp"];
[clampFilter setValue:inputImage forKey:kCIInputImageKey];
[clampFilter setValue:[NSValue valueWithBytes:&transform objCType:@encode(CGAffineTransform)] forKey:@"inputTransform"];

CIImage *outputImage = [clampFilter outputImage];

CIFilter *blurFilter = [CIFilter filterWithName:@"CIGaussianBlur"
     keysAndValues:kCIInputImageKey, outputImage, @"inputRadius", [NSNumber numberWithFloat:radius], nil];

outputImage = [blurFilter outputImage];

CGImageRef cgimg = [context createCGImage:outputImage fromRect:[outputImage extent]];
UIImage *blurredImage = [UIImage imageWithCGImage:cgimg];
CGImageRelease(cgimg);

推荐答案

CIAffineClamp过滤器将您的范围设置为无限，然后混淆你的背景。尝试保存预钳位范围CGRect，然后将其提供给上下文初始化程序。

The CIAffineClamp filter is setting your extent as infinite, which then confounds your context. Try saving off the pre-clamp extent CGRect, and then supplying that to the context initializer.

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