通过Core Image添加滤镜

by : http://cocacola-ty.github.io

处理过程

1. 读取图片

   1. 读取UIImage类型图片

   2. 将UIImage转为NSData

   3. 根据NSData转为CIImage

2. 处理滤镜

   1. 创建滤镜。根据滤镜名称初始化一个滤镜

   2. 设置滤镜参数

   3. 设置滤镜图片输入源，即设置滤镜的inputImage参数

3. 处理进行过滤镜的图片

   1. 获取CIContext，通过该对象将滤镜的输出图像进行处理

   2. 通过CIContext对象获取滤镜的输出对象并将图像转换为CGImage

   3. 将CGImage转换为UIImage

主要类

• CIContext: Core Image处理上下文，图像处理在该类完成

• CIFilter：滤镜类，定义各种滤镜的属性。各种滤镜都属于该类

• CIImage：保存图像数据

实例

        /******读取图片部分******/
    // 读取图片
    NSString *path = [[NSBundle mainBundle] pathForResource:@"2" ofType:@"jpg"];
    UIImage *image = [UIImage imageWithContentsOfFile:path];
    
    // 将UIImage转CIImage
    NSData *data = UIImagePNGRepresentation(image);
    CIImage *inputImage = [CIImage imageWithData:data];
    

    /******处理滤镜部分******/
    // 初始化进行滤镜的颜色
    CIColor *sepiaColor = [CIColor colorWithRed:0.76 green:0.65 blue:0.54];
    
    // 通过滤镜名称创建滤镜 初始化滤镜参数
    CIFilter *monochromeFilter = [CIFilter filterWithName:@"CIColorMonochrome" withInputParameters:@{@"inputColor":sepiaColor,@"inputIntensity":@1.0}];
    // 设置滤镜的输入图像
    [monochromeFilter setValue:inputImage forKey:@"inputImage"];
    
    // 根据滤镜名称创建滤镜 初始化滤镜基本参数
    CIFilter *vinFilter = [CIFilter filterWithName:@"CIVignette" withInputParameters:@{@"inputRadius":@1.75,@"inputIntensity":@1.0}];
    // 以经过上一个滤镜处理的图像作为本次滤镜的输入图像
    [vinFilter setValue:monochromeFilter.outputImage forKey:@"inputImage"];
    
    // 获取经过两次滤镜的图像
    CIImage *outputImage = vinFilter.outputImage;
    
    // 创建高斯模糊滤镜
    CIFilter *blur = [CIFilter filterWithName:@"CIGaussianBlur" withInputParameters:@{@"inputRadius":@40}];
    [blur setValue:inputImage forKey:@"inputImage"];
    

    /******处理滤镜之后图片部分******/
    // 将CIImage转换为CGImage 再转为UIImage
    CIContext *context = [CIContext contextWithOptions:nil];
    struct CGImage *cgImage = [context createCGImage:blur.outputImage fromRect:inputImage.extent];
    
    UIImage *outputUIImage = [UIImage imageWithCGImage:cgImage];
    
    // 显示处理后的图片
    UIImageView *imgView = [[UIImageView alloc] init];
    imgView.frame = CGRectMake(40, 40, 200, 200);
    imgView.image = outputUIImage ;
    [self.view addSubview:imgView];

获取可用的滤镜列表

  // 所有可用的滤镜
    NSLog(@"可用的滤镜\n%@",[CIFilter filterNamesInCategory:kCICategoryBuiltIn])

获取滤镜的属性

    // 滤镜的属性
    NSLog(@"%@",blurFilter.attributes)

// 输出结果为：

{
    "CIAttributeFilterAvailable_Mac" = "10.4";
    "CIAttributeFilterAvailable_iOS" = 6;
    CIAttributeFilterCategories =     (
        CICategoryBlur,
        CICategoryStillImage,
        CICategoryVideo,
        CICategoryBuiltIn
    );
    CIAttributeFilterDisplayName = "Gaussian Blur";
    CIAttributeFilterName = CIGaussianBlur;
    CIAttributeReferenceDocumentation = "http://developer.apple.com/cgi-bin/apple_ref.cgi?apple_ref=//apple_ref/doc/filter/ci/CIGaussianBlur";
    inputImage =     {
        CIAttributeClass = CIImage;
        CIAttributeDescription = "The image to use as an input image. For filters that also use a background image, this is the foreground image.";
        CIAttributeDisplayName = Image;
        CIAttributeType = CIAttributeTypeImage;
    };
    inputRadius =     {
        CIAttributeClass = NSNumber;
        CIAttributeDefault = 10;
        CIAttributeDescription = "The radius determines how many pixels are used to create the blur. The larger the radius, the blurrier the result.";
        CIAttributeDisplayName = Radius;
        CIAttributeIdentity = 0;
        CIAttributeMin = 0;
        CIAttributeSliderMax = 100;
        CIAttributeSliderMin = 0;
        CIAttributeType = CIAttributeTypeScalar;
    };
}

inputXX即该滤镜的输入参数。(当前滤镜中即inputRadius)

这样，通过查询滤镜的attributes的inputXX数组我们可以得到滤镜的输入参数来设置滤镜的显示效果

详细解释输入参数数组

• CIAttributeClass -- 该属性接收的类型

• CIAttributeDefault -- 该属性的默认值

• CIAttributeDescription -- 该属性的描述

• CIAttributeDisplayName -- 该属性的名称

• CIAttributeIdentity -- 属性标识

• CIAttributeMin -- 属性最小值

• CIAttributeSliderMax -- 属性最大值

• CIAttributeType -- 属性类型