iOS中滤镜的使用（二）滤镜组合_ios cifilter cimasktoalpha

iOS中滤镜的使用（二）

滤镜组合

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首先 要加载图片并转化为CIImage

CIImage *ciImage = [[CIImage alloc] initWithImage:[UIImage imageNamed:@"IMG_0160"]];
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其次，创建filter滤镜

 CIFilter *filterOne = [CIFilter filterWithName:@"CIPixellate"];//马赛克滤镜

    NSLog(@"%@",filterOne.attributes);
    [filterOne setValue:ciImage  forKey:kCIInputImageKey];
    [filterOne setDefaults];
    CIImage *outImage = [filterOne valueForKey:kCIOutputImageKey];

    CIFilter *filterTwo = [CIFilter filterWithName:@"CIHueAdjust"];//饱和度滤镜

    [filterTwo setValue:outImage  forKey:kCIInputImageKey];
    [filterTwo setDefaults];

    NSLog(@"%@",filterTwo.attributes);//打印可修改的属性
    [filterTwo setValue:@(3.14) forKey:kCIInputAngleKey];//位置不能改变

    CIImage *outImageTwo = [filterTwo valueForKey:kCIOutputImageKey];
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然后，用CIContext将滤镜中的图片渲染出来，原因，导出图片过过程中用到CGImageRef。

CIContext *context = [CIContext contextWithOptions:nil];

CGImageRef cgImage = [context createCGImage:outImage fromRect:[outImage extent]];
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最后，导出图片，注意内存的释放

 UIImage *showImage = [UIImage imageWithCGImage:cgImage];

CGImageRelease(cgImage);
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剩下的工作就是加载马赛克图片了

 UIImageView *imageView = [[UIImageView alloc] initWithFrame: CGRectMake(
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