iOS滤镜

// 对静态图像进行模糊处理
- (UIImage *)blurImage:(CGImageRef)srcImg {
    // 创建CIContext，这里关闭color management有助于提升性能
    NSDictionary *options = @{ kCIContextWorkingColorSpace : [NSNull null] };
    CIContext *mContext = [CIContext contextWithOptions:options];

    CIImage *mImg = [[CIImage alloc] initWithCGImage:srcImg];
    // 创建高斯模糊滤镜，ios只支持这1种模糊滤镜，并且要ios6.0以上才行，inputRadius最大100，默认10
    CIFilter *mBlurFilter = [CIFilter filterWithName:@"CIGaussianBlur"];
    [mBlurFilter setValue:mImg forKey:kCIInputImageKey];
    [mBlurFilter setValue:@(10.0f) forKey:@"inputRadius”];
    CIImage *mBlurImg = [mBlurFilter valueForKey:kCIOutputImageKey];
    CGImageRef mResultCGImg = [mContext createCGImage:mBlurImg fromRect:[mBlurImg extent]];
    UIImage *mResultUIImg = [UIImage imageWithCGImage:mResultCGImg];
    CGImageRelease(mDestImg);
    [mImg release];

    return mResultUIImg;
}

// 对摄像头作模糊处理
// 使用AVFoundation实现摄像头功能并且实现AVCaptureVideoDataOutputSampleBufferDelegate托管协议
- (void)captureOutput:(AVCaptureOutput *)captureOutput didOutputSampleBuffer:(CMSampleBufferRef)sampleBuffer fromConnection:(AVCaptureConnection *)connection {
    CVImageBufferRef imageBuffer = CMSampleBufferGetImageBuffer(sampleBuffer);
    CVPixelBufferLockBaseAddress(imageBuffer, 0);
    void *baseAddress = CVPixelBufferGetBaseAddress(imageBuffer);
    size_t bytesPerRow = CVPixelBufferGetBytesPerRow(imageBuffer);
    size_t width = CVPixelBufferGetWidth(imageBuffer);
    size_t height = CVPixelBufferGetHeight(imageBuffer);
   
    static CGColorSpaceRef colorSpace = nil;
    if (colorSpace == nil) {
        colorSpace = CGColorSpaceCreateDeviceRGB();
    }
   
    CGContextRef context = CGBitmapContextCreate(baseAddress, width, height, 8, bytesPerRow, colorSpace, kCGBitmapByteOrder32Little | kCGImageAlphaPremultipliedFirst);
    CGImageRef quartzImage = CGBitmapContextCreateImage(context);
   

    // 处理原始图像
    UIImage *resultUIImage = [self blurImage:quartzImage];
    // 更新某个UIImageView的image（隐藏摄像头的layer，盖一个UIImageView来播放滤镜处理后的图像）
    ...
   
    CGImageRelease(quartzImage);
    CGContextRelease(context);
    CVPixelBufferUnlockBaseAddress(imageBuffer,0);
}


参考：
1. Core Image Programming Guide
https://developer.apple.com/library/ios/documentation/GraphicsImaging/Conceptual/CoreImaging/ci_performance/ci_performance.html#//apple_ref/doc/uid/TP30001185-CH10-SW2

2. Core Image Filter Reference
https://developer.apple.com/library/ios/documentation/GraphicsImaging/Reference/CoreImageFilterReference/Reference/reference.html#//apple_ref/doc/uid/TP40004346