我正在使用 GPUImage 过滤器创建一个简单的图像亮度、对比度和饱和度调整工具。该 View 有一个 ImageView 和每个过滤器的 3 个 slider 。起初我以为我会在每个 slider 的值发生变化时应用每个过滤器，但后来我意识到必须链接过滤器。所以我写了下面的代码。此代码的问题在于仅将亮度滤镜应用于图像。

- (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;


}

现在我决定以更简单的方式实现整个事情，但我仍然一无所获:

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;

最佳答案

您不需要为每个 slider 更改使用相同的添加目标代码。您应该只更改所需过滤器的值并在代码的其他地方设置所有过滤器；您最终将加载图像的位置。这将使您的代码更易于维护，并使这个问题更短。

现在进入实际问题。查看 GPUImage github issue .您已按以下顺序嵌套过滤器:

静止图像 > 亮度 > 对比度 > 饱和度

然后您将从亮度过滤器获取图像。您需要通过饱和度过滤器来获取它。所以，你的链需要像这样:

静止图像>亮度>对比度>饱和度>输出图像

关于ios - 使用 UISlider 应用 GPUImage 过滤器，我们在Stack Overflow上找到一个类似的问题： https://stackoverflow.com/questions/29897180/