CIGaussianBlur图像大小

Question

嘿想模糊我的观点，我使用这段代码：

//Get a UIImage from the UIView
NSLog(@"blur capture");
UIGraphicsBeginImageContext(BlurContrainerView.frame.size);
[self.view.layer renderInContext:UIGraphicsGetCurrentContext()];
UIImage *viewImage = UIGraphicsGetImageFromCurrentImageContext();
UIGraphicsEndImageContext();

//Blur the UIImage
CIImage *imageToBlur = [CIImage imageWithCGImage:viewImage.CGImage];
CIFilter *gaussianBlurFilter = [CIFilter filterWithName: @"CIGaussianBlur"];
[gaussianBlurFilter setValue:imageToBlur forKey: @"inputImage"];
[gaussianBlurFilter setValue:[NSNumber numberWithFloat: 5] forKey: @"inputRadius"]; //change number to increase/decrease blur
CIImage *resultImage = [gaussianBlurFilter valueForKey: @"outputImage"];

//create UIImage from filtered image
blurredImage = [[UIImage alloc] initWithCIImage:resultImage];

//Place the UIImage in a UIImageView
UIImageView *newView = [[UIImageView alloc] initWithFrame:self.view.bounds];
newView.image = blurredImage;

NSLog(@"%f,%f",newView.frame.size.width,newView.frame.size.height);
//insert blur UIImageView below transparent view inside the blur image container
[BlurContrainerView insertSubview:newView belowSubview:transparentView];

它使观点模糊，但不是全部。我怎样才能模糊所有的视图？

Answer 1

问题不在于它不会使所有图像模糊，而是模糊会扩展图像的边界，使图像更大，并且因此不能正确排列。

要使图像保持相同的大小，请执行以下行：

CIImage *resultImage    = [gaussianBlurFilter valueForKey: @"outputImage"];

您可以抓取CGRect获取原始图片大小的矩形resultImage：

// note, adjust rect because blur changed size of image

CGRect rect             = [resultImage extent];
rect.origin.x          += (rect.size.width  - viewImage.size.width ) / 2;
rect.origin.y          += (rect.size.height - viewImage.size.height) / 2;
rect.size               = viewImage.size;

然后使用CIContext抓取图片的那一部分：

CIContext *context      = [CIContext contextWithOptions:nil];
CGImageRef cgimg        = [context createCGImage:resultImage fromRect:rect];
UIImage   *blurredImage = [UIImage imageWithCGImage:cgimg];
CGImageRelease(cgimg);

---

或者，对于iOS 7，如果您转到iOS UIImageEffects sample code并下载iOS_UIImageEffects.zip，则可以获取UIImage+ImageEffects类别。无论如何，这提供了一些新的方法：

- (UIImage *)applyLightEffect;
- (UIImage *)applyExtraLightEffect;
- (UIImage *)applyDarkEffect;
- (UIImage *)applyTintEffectWithColor:(UIColor *)tintColor;
- (UIImage *)applyBlurWithRadius:(CGFloat)blurRadius tintColor:(UIColor *)tintColor saturationDeltaFactor:(CGFloat)saturationDeltaFactor maskImage:(UIImage *)maskImage;

因此，为了模糊和成像并使其变亮（给予“磨砂玻璃”效果），您可以这样做：

UIImage *newImage = [image applyLightEffect];

有趣的是，Apple的代码不使用CIFilter，而是调用vImageBoxConvolve_ARGB8888的vImage high-performance image processing framework。 WWDC 2013视频Implementing Engaging UI on iOS中说明了这种技术。

Answer 2

更快的解决方案是完全避免使用CGImageRef并在CIImage惰性级别执行所有转换。

所以，而不是你的不合适：

// cropping rect because blur changed size of image
CIImage *croppedImage = [resultImage imageByCroppingToRect:imageToBlur.extent];
// create UIImage from filtered cropped image
blurredImage = [[UIImage alloc] initWithCIImage:croppedImage];

一个很好的解决方案是写：

目标C

// cropping rect because blur changed size of image
let croppedImage = resultImage.cropping(to: imageToBlur.extent)
// create UIImage from filtered cropped image
let blurredImage = UIImage(ciImage: croppedImage)

Swift 3

// cropping rect because blur changed size of image
let croppedImage = resultImage.cropped(to: imageToBlur.extent)
// create UIImage from filtered cropped image
let blurredImage = UIImage(ciImage: croppedImage)

Swift 4

val list = List(50176482, 50176481, 50176485, 50176479, 50176478, 51176477, 51176483, 51176480)
val list1 = list.filter(_.toString.substring(0, 2) == "50")
val list2 = list.filter(_.toString.substring(0, 2) == "51")
println(list1)
println(list2)

Answer 3

看起来模糊滤镜会给你一个比你开始时更大的图像，这是有道理的，因为边缘处的像素越来越模糊。最简单的解决方案可能是让newView使用contentMode UIViewContentModeCenter，这样就不会试图压缩模糊的图像;你也可以通过在适当大小的新上下文的中心绘制它来裁剪blurredImage，但你真的不需要。{/ p>