比如对图片进行实时亮度调整

用GPUImage处理如下

self.brightnessFilter = [[GPUImageBrightnessFilter alloc] init]; self.imagePicture = [[GPUImagePicture alloc] initWithImage:_originImage]; [self.imagePicture addTarget:_brightnessFilter]; [self.imagePicture processImage];

- (IBAction)valueChangeAction:(UISlider *)brightnessSlider{ [self.brightnessFilter setBrightness:[brightnessSlider value]]; self.editImageView.image = [self.brightnessFilter imageByFilteringImage:_originImage]; }

1. [self.brightnessFilter imageByFilteringImage:_originImage];这个获取处理后图片的方法是否正确，看到stackoverflow上的回答都是[self.brightnessFilter imageFromCurrentlyProcessedOutput]这样来获取的，但这个方法貌似已经弃用了，哪种方法才是正确的，还是我前面的代码也有问题？

2. iPhone 5s真机调试发现实时的调整会存在卡顿的现象，但原始图片质量并不是很高，尝试过异步的方案，仍然会出现卡顿，具体要如何处理才能避免这种情况？

dispatch_async(dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_DEFAULT, 0), ^{ [self.brightnessFilter setBrightness:[brightnessSlider value]]; dispatch_async(dispatch_get_main_queue(), ^{ self.editImageView.image = [self.brightnessFilter imageByFilteringImage:_originImage]; }); });