應用與UISlider GPUImage過濾器

Question

我使用GPUImage過濾器來創建一個簡單的圖像亮度，對比度和飽和度調整工具。視圖有一個圖像視圖，每個過濾器有三個滑塊。起初我以爲我會應用每個過濾器作爲每個滑塊的價值改變，但後來我意識到，過濾器必須鏈接。所以我寫了下面的代碼。這個代碼的問題是隻有亮度過濾器應用於圖像。

- (IBAction)brightnessSlider:(UISlider *)sender { 

    brightnessValue = sender.value; 

    UIImage *inputImage = [UIImage imageNamed:@"2.jpg"]; 

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

    GPUImageBrightnessFilter *brightnessFilter = [GPUImageBrightnessFilter new]; 
    GPUImageContrastFilter *contrastFilter = [GPUImageContrastFilter new]; 
    GPUImageSaturationFilter *saturationFilter = [GPUImageSaturationFilter new]; 

    [brightnessFilter setBrightness:brightnessValue]; 
    [contrastFilter setContrast:contrastValue]; 
    [saturationFilter setSaturation:saturationValue]; 

    [stillImageSource addTarget:brightnessFilter]; 
    [brightnessFilter addTarget:contrastFilter]; 
    [contrastFilter addTarget:saturationFilter]; 
    [brightnessFilter useNextFrameForImageCapture]; 
    [stillImageSource processImage]; 

    UIImage *currentFilteredVideoFrame = [brightnessFilter imageFromCurrentFramebuffer]; 

    imageView.image = currentFilteredVideoFrame; 
} 

- (IBAction)contrastSlider:(UISlider *)sender 
{ 
    contrastValue = sender.value; 

    UIImage *inputImage = [UIImage imageNamed:@"2.jpg"]; 

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

    GPUImageBrightnessFilter *brightnessFilter = [GPUImageBrightnessFilter new]; 
    GPUImageContrastFilter *contrastFilter = [GPUImageContrastFilter new]; 
    GPUImageSaturationFilter *saturationFilter = [GPUImageSaturationFilter new]; 

    [brightnessFilter setBrightness:brightnessValue]; 
    [contrastFilter setContrast:contrastValue]; 
    [saturationFilter setSaturation:saturationValue]; 

    [stillImageSource addTarget:brightnessFilter]; 
    [brightnessFilter addTarget:contrastFilter]; 
    [contrastFilter addTarget:saturationFilter]; 
    [brightnessFilter useNextFrameForImageCapture]; 
    [stillImageSource processImage]; 

    UIImage *currentFilteredVideoFrame = [brightnessFilter imageFromCurrentFramebuffer]; 

    imageView.image = currentFilteredVideoFrame; 
} 


- (IBAction)saturationSlider:(UISlider *)sender 
{ 
    saturationValue = sender.value; 

    UIImage *inputImage = [UIImage imageNamed:@"2.jpg"]; 

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

    GPUImageBrightnessFilter *brightnessFilter = [GPUImageBrightnessFilter new]; 
    GPUImageContrastFilter *contrastFilter = [GPUImageContrastFilter new]; 
    GPUImageSaturationFilter *saturationFilter = [GPUImageSaturationFilter new]; 

    [brightnessFilter setBrightness:brightnessValue]; 
    [contrastFilter setContrast:contrastValue]; 
    [saturationFilter setSaturation:saturationValue]; 

    [stillImageSource addTarget:brightnessFilter]; 
    [brightnessFilter addTarget:contrastFilter]; 
    [contrastFilter addTarget:saturationFilter]; 
    [brightnessFilter useNextFrameForImageCapture]; 
    [stillImageSource processImage]; 

    UIImage *currentFilteredVideoFrame = [brightnessFilter imageFromCurrentFramebuffer]; 

    imageView.image = currentFilteredVideoFrame; 


} 

現在我決定實施一個更簡單的方法了整個事情，但我仍然得到什麼：

UIImage *inputImage = [UIImage imageNamed:@"2.jpg"]; 
    GPUImagePicture *stillImageSource = [[GPUImagePicture alloc] initWithImage:inputImage]; 

    //Set Brightness to 60 
    GPUImageBrightnessFilter *brightnessFilter = [GPUImageBrightnessFilter new]; 
    [brightnessFilter setBrightness:60.0]; 

    //Set Contrast to 12 
    GPUImageContrastFilter *contrastFilter = [GPUImageContrastFilter new]; 
    [contrastFilter setContrast:12]; 


    [brightnessFilter addTarget:contrastFilter]; 

    [stillImageSource addTarget:contrastFilter]; 
    [contrastFilter useNextFrameForImageCapture]; 
    [stillImageSource processImage]; 

    UIImage *outputImage1 = [contrastFilter imageFromCurrentFramebuffer]; 
    imageView.image = outputImage1; 

Answer 1

你並不需要使用相同的附加目標代碼每個滑塊改變。您應該只更改所需過濾器的值並在代碼中的其他位置設置所有過濾器;你將最終加載圖像。這會讓你的代碼更容易維護，並且會縮短這個問題。

現在到了實際問題。查看GPUImage github issue。你已經按以下順序嵌套過濾器：

靜止圖像>亮度>對比度>飽和度

然後，你都可以從亮度過濾圖像。你需要通過飽和度過濾器。所以，你的鏈條需要像：

靜止圖像>亮度>對比度>飽和度>輸出圖像