iOS 影像處理 － 模糊映像

iOS 影像處理 － 模糊映像

解決問題：將映像模糊

前提：添加 CoreGraphics.framework

源碼：

- (UIImage*) blur:(UIImage*)theImage{    // create our blurred image    CIContext *context = [CIContext contextWithOptions:nil];    CIImage *inputImage = [CIImage imageWithCGImage:theImage.CGImage];        // setting up Gaussian Blur (could use one of many filters offered by Core Image)    CIFilter *blurFilter = [CIFilter filterWithName:@"CIGaussianBlur"];    [blurFilter setValue:inputImage forKey:kCIInputImageKey];    [blurFilter setValue:[NSNumber numberWithFloat:10.0f] forKey:@"inputRadius"];    CIImage *result = [blurFilter valueForKey:kCIOutputImageKey];        // CIGaussianBlur has a tendency to shrink the image a little,    // this ensures it matches up exactly to the bounds of our original image    CGImageRef cgImage = [context createCGImage:result fromRect:[inputImage extent]];        UIImage *returnImage = [UIImage imageWithCGImage:cgImage];    //create a UIImage for this function to "return" so that ARC can manage the memory of the blur...    //ARC can't manage CGImageRefs so we need to release it before this function "returns" and ends.    CGImageRelease(cgImage);//release CGImageRef because ARC doesn't manage this on its own.        return returnImage;}

出現問題：因為在模糊的時候，邊緣會變成半透明的狀態，所以理想狀況是可以對原映像進行適當放大，選擇使用CIAffineClamp在模糊之前對映像進行處理。

源碼：

- (UIImage*) blur:(UIImage*)theImage{    // create our blurred image    CIContext *context = [CIContext contextWithOptions:nil];    CIImage *inputImage = [CIImage imageWithCGImage:theImage.CGImage];        CIFilter *affineClampFilter = [CIFilter filterWithName:@"CIAffineClamp"];    CGAffineTransform xform = CGAffineTransformMakeScale(1.0, 1.0);    [affineClampFilter setValue:inputImage forKey:kCIInputImageKey];    [affineClampFilter setValue:[NSValue valueWithBytes:&xform                                               objCType:@encode(CGAffineTransform)]                                                 forKey:@"inputTransform"];        CIImage *extendedImage = [affineClampFilter valueForKey:kCIOutputImageKey];        // setting up Gaussian Blur (could use one of many filters offered by Core Image)    CIFilter *blurFilter = [CIFilter filterWithName:@"CIGaussianBlur"];    [blurFilter setValue:extendedImage forKey:kCIInputImageKey];    [blurFilter setValue:[NSNumber numberWithFloat:10.0f] forKey:@"inputRadius"];    CIImage *result = [blurFilter valueForKey:kCIOutputImageKey];        // CIGaussianBlur has a tendency to shrink the image a little,    // this ensures it matches up exactly to the bounds of our original image    CGImageRef cgImage = [context createCGImage:result fromRect:[inputImage extent]];        UIImage *returnImage = [UIImage imageWithCGImage:cgImage];    //create a UIImage for this function to "return" so that ARC can manage the memory of the blur...    //ARC can't manage CGImageRefs so we need to release it before this function "returns" and ends.    CGImageRelease(cgImage);//release CGImageRef because ARC doesn't manage this on its own.        return returnImage;}

參考：（網上資源，部分連結已丟失）

http://stackoverflow.com/questions/12839729/correct-crop-of-cigaussianblur