如何添加多个过滤器到UIImage GPUImage？

Question

我注意到很多人问关于使用GPUImage链接过滤器的问题。我无法弄清楚如何简洁地做到这一点。终于在今晚工作。只是想分享我的代码，以便人们可以链接到解决方案。

Answer 1

UIImage *faceImage = [UIImage imageNamed:@"469453586_640.jpg"]; 
UIImageView *face = [[UIImageView alloc] initWithFrame:CGRectMake(0.0, 0.0, faceImage.size.width/2.0, faceImage.size.height/2.0)]; 
[face setImage:faceImage]; 
[self.view addSubview:face]; 

GPUImagePicture *stillImageSource = [[GPUImagePicture alloc] initWithImage:faceImage]; 

GPUImageBrightnessFilter *brightnessFilter = [[GPUImageBrightnessFilter alloc] init]; 
[brightnessFilter setBrightness:.15]; 
GPUImageGrayscaleFilter *grayscaleFilter = [[GPUImageGrayscaleFilter alloc] init]; 

GPUImagePosterizeFilter *posterizeFilter = [[GPUImagePosterizeFilter alloc] init]; 
[posterizeFilter setColorLevels:1]; 


[stillImageSource addTarget:brightnessFilter]; 
[brightnessFilter addTarget:grayscaleFilter]; 
[grayscaleFilter addTarget:posterizeFilter]; 

// these need to be changed if you change the order of your filters 
// [brightnessFilter useNextFrameForImageCapture]; 
// [grayscaleFilter useNextFrameForImageCapture]; 
[posterizeFilter useNextFrameForImageCapture]; 

[stillImageSource processImage]; 

[face setImage: [posterizeFilter imageFromCurrentFramebuffer]];