图片模糊效果
背景虚化(模糊)的效果越来越常用,那么如何使用代码来实现呢?在上篇文章中,我们讨论了关于 CoreImage 的知识, 理所当然的,首先尝试使用 CoreImage 解决问题,从上次打印出来的所有支持的滤镜中,在 127种滤镜中,存在 Blur 关键字的,只有CIGaussianBlur(高斯模糊),,而这种模糊的致命缺陷是,会出现白边.(懂美术的同学可能知道,这是位图和矢量图的原因) 高斯模糊代码
CIContext *context = [CIContext contextWithOptions:nil];CIImage *inputImage = [[CIImage alloc] initWithImage:[UIImage imageNamed:@”1.png”]];// create gaussian blur filterCIFilter *filter = [CIFilter filterWithName:@”CIGaussianBlur”];[filter setValue:inputImage forKey:kCIInputImageKey];[filter setValue:[NSNumber numberWithFloat:10.0] forKey:@”inputRadius”];// blur imageCIImage *result = [filter valueForKey:kCIOutputImageKey];CGImageRef cgImage = [context createCGImage:result fromRect:[result extent]];UIImage *image = [UIImage imageWithCGImage:cgImage];CGImageRelease(cgImage);self.mainImageView.image = image;
那么依照我现在的知识,使用 CoreImage 就没法解决问题了… 通过查找参考资料,发现 iOS5.0中新增了vImage API可以使用，它属于Accelerate.Framework，，所以如果你要使用它要在工程中加入这个Framework。模糊算法使用的是vImageBoxConvolve_ARGB8888这个函数
-(UIImage *)blurryImage:(UIImage *)image withBlurLevel:(CGFloat)blur {if (blur < 0.f || blur > 1.f) {blur = 0.5f;}int boxSize = (int)(blur * 100);boxSize = boxSize – (boxSize % 2) + 1;CGImageRef img = image.CGImage;vImage_Buffer inBuffer, outBuffer;vImage_Error error;void *pixelBuffer;CGDataProviderRef inProvider = CGImageGetDataProvider(img);CFDataRef inBitmapData = CGDataProviderCopyData(inProvider);inBuffer.width = CGImageGetWidth(img);inBuffer.height = CGImageGetHeight(img);inBuffer.rowBytes = CGImageGetBytesPerRow(img);inBuffer.data = (void*)CFDataGetBytePtr(inBitmapData);pixelBuffer = malloc(CGImageGetBytesPerRow(img) *CGImageGetHeight(img));if(pixelBuffer == NULL)NSLog(@”No pixelbuffer”);outBuffer.data = pixelBuffer;outBuffer.width = CGImageGetWidth(img);outBuffer.height = CGImageGetHeight(img);outBuffer.rowBytes = CGImageGetBytesPerRow(img);error = vImageBoxConvolve_ARGB8888(&inBuffer,&outBuffer,NULL,0,0,boxSize,boxSize,NULL,kvImageEdgeExtend);if (error) {NSLog(@”error from convolution %ld”, error);}CGColorSpaceRef colorSpace = CGColorSpaceCreateDeviceRGB();CGContextRef ctx = CGBitmapContextCreate(outBuffer.data,outBuffer.width,outBuffer.height,8,outBuffer.rowBytes,colorSpace,kCGImageAlphaNoneSkipLast);CGImageRef imageRef = CGBitmapContextCreateImage (ctx);UIImage *returnImage = [UIImage imageWithCGImage:imageRef];//clean upCGContextRelease(ctx);CGColorSpaceRelease(colorSpace);free(pixelBuffer);CFRelease(inBitmapData);CGColorSpaceRelease(colorSpace);CGImageRelease(imageRef);return returnImage;}
最终效果:
“人无完人金无足赤”，只要是人就不会是完美的，
