QQ20180828-154120@2x.png

至于該濾鏡的初始化和自定義，可以參考GPUImage官方寫好的濾鏡GPUImageAmatorkaFilter來寫。

GPUImageToneCurveFilter需要個顏色曲線文件，這個文件是一個acv格式的文件，使用的時候用initWithACVURL這個方法初始化，url可以是本地的url（沒有嘗試網(wǎng)絡(luò)url）
以下片段是把色調(diào)曲線濾鏡加到了攝像頭上，實時渲染

    NSBundle *bundle = [NSBundle bundleForClass:self.class];
    NSURL *filterAmaro = [NSURL fileURLWithPath:[bundle pathForResource:@"fugu" ofType:@"acv"]];
    self.toneCurveFilter = [[GPUImageToneCurveFilter alloc] initWithACVURL:filterAmaro];

    GPUImageBeautifyFilter *beautifyFilter = [[GPUImageBeautifyFilter alloc] init];
    [self.camera addTarget:beautifyFilter];
    [beautifyFilter addTarget:self.toneCurveFilter];
    [self.toneCurveFilter addTarget:self.preview];
    [self.camera startCameraCapture];

以下片段是把色調(diào)曲線濾鏡加到圖片上，渲染

+ (UIImage *)applyFIlter:(UIImage *)originalImg withCurrentFilterName:(NSString *)filterName{
    
    UIImage *inputImage =originalImg;
    
    UIImage *outputImage = nil;
    
    GPUImagePicture *stillImageSource = [[GPUImagePicture alloc] initWithImage:inputImage];
    
    //添加濾鏡
    
    NSBundle *bundle = [NSBundle bundleForClass:self.class];
    NSURL *filterAmaro = [NSURL fileURLWithPath:[bundle pathForResource:filterName ofType:@"acv"]];
    
    GPUImageToneCurveFilter *toneCurveFilter = [[GPUImageToneCurveFilter alloc] initWithACVURL:filterAmaro];
    //導(dǎo)入之前保存的NewLookupTable.png文件
    FSKGPUImageBeautyFilter *beautyFilter = [[FSKGPUImageBeautyFilter alloc] init];
    GPUImageFilterGroup *group = [[GPUImageFilterGroup alloc] init];
    [self addGPUImageFilterFromGroup:group withGPUImageFilter:toneCurveFilter];
    [self addGPUImageFilterFromGroup:group withGPUImageFilter:beautyFilter];
    
    
    [stillImageSource addTarget:group];//相當于retain，不加這一句，濾鏡會被提前釋放導(dǎo)致系統(tǒng)崩潰
    
    [group useNextFrameForImageCapture];
    
    if([stillImageSource processImageWithCompletionHandler:nil]) {
        
        outputImage= [group imageFromCurrentFramebuffer];
        
    }
    
    return outputImage;
    
}
+ (void)addGPUImageFilterFromGroup:(GPUImageFilterGroup *)myFilterGroup withGPUImageFilter:(GPUImageFilter *)filter{
    
    [myFilterGroup addFilter:filter];
    
    GPUImageOutput<GPUImageInput> *newTerminalFilter = filter;
    
    NSInteger count = myFilterGroup.filterCount;
    
    if (count == 1)
    {
        //設(shè)置初始濾鏡
        myFilterGroup.initialFilters = @[newTerminalFilter];
        //設(shè)置末尾濾鏡
        myFilterGroup.terminalFilter = newTerminalFilter;
        
    } else
    {
        GPUImageOutput<GPUImageInput> *terminalFilter    = myFilterGroup.terminalFilter;
        NSArray *initialFilters                          = myFilterGroup.initialFilters;
        
        [terminalFilter addTarget:newTerminalFilter];
        
        //設(shè)置初始濾鏡
        myFilterGroup.initialFilters = @[initialFilters[0]];
        //設(shè)置末尾濾鏡
        myFilterGroup.terminalFilter = newTerminalFilter;
    }
}

上面兩種情況下都是加上了美顏濾鏡，如果不需要的話，直接去掉就行