11 (OC)* CoreImage

1. coreimage framework 组成

　　　　apple 已经帮我们把image的处理分类好，来看看它的结构：

　　　　　　主要分为三部分：

　　　　　　　　1）定义部分：CoreImage 何CoreImageDefines。见名思义，代表了CoreImage 这个框架和它的定义。

　　　　　　　　2）操作部分：

　　　　　　　　　　　　　　滤镜（CIFliter）：CIFilter 产生一个CIImage。典型的，接受一到多的图片作为输入，经过一些过滤操作，产生指定输出的图片。

　　　　　　　　　　　　　　检测（CIDetector）：CIDetector 检测处理图片的特性，如使用来检测图片中人脸的眼睛、嘴巴、等等。

　　　　　　　　　　　　　　特征（CIFeature）：CIFeature 代表由 detector处理后产生的特征。

　　　　　　　　3）图像部分：

　　　　　　　　　　　　　　画布（CIContext）：画布类可被用与处理Quartz 2D 或者 OpenGL。可以用它来关联CoreImage类。如滤镜、颜色等渲染处理。

　　　　　　　　　　　　　　颜色（CIColor）：   图片的关联与画布、图片像素颜色的处理。

　　　　　　　　　　　　　　向量（CIVector）： 图片的坐标向量等几何方法处理。

　　　　　　　　　　　　　　图片（CIImage）： 代表一个图像，可代表关联后输出的图像。　　

　　2.  处理步骤：

　　　　1）create a ciimage object;

　　　　2) create a cifilter object and set input values

　　　　3)  create a cicontext object.

　　　　4) render the filter output image into a cgimage

　　　　

　　3.注意

　　　　a。关注Ciimage 产生的途径：

　　　　　　　　1）通过URL和Data

　　　　　　　　 2）通过其他图片类转换，CGImageRef或其他图片。

　　　　　　　　 3）通过CVpixelBufferRef。

　　　　　　　　 4）一组像素Data。

　　　　b.  图片颜色，KCCImageColorSpace 来重载默认颜色空间。

　　　　c. 图片Metadata。

　　　　

　　4. 使用滤镜。

　　　　CISepiaTone、CiColorControls、CIHueBlendMode。

  

处理过程：多个CImage输入 －－ 》 CIHeBlendMode  －－》 CiSepiatone。

渲染输出：

　　

　　

流程： 获取context  －》 转成CIimage －》 渲染成CGImageRef  －》 转换为UIimage －》 释放 CGImageRef －》 使用UIImage。

5.脸部检测

　　自动增强： CIRedEyeCorrection  、CIFaceBalance（调整图片来给出更好的皮肤色调）、CIVibrance（在不扭曲皮肤色调的情况下，增加饱和度）、CIToneCurve（调整图片对比）、高亮阴影调整。

CoreImage框架是一个专门用来对图片进行处理的框架，其中提供了许多高级功能，可以帮助开发者完成UIKit或者CoreGraphics框架无法完成的任务，并且使用CoreImage框架可以十分轻松的实现滤镜以及图像识别等流行技术。本篇博客主要介绍和总结CoreImage框架的使用，并提供范例代码。

一、图像过滤器

1.几组内置的过滤器

CIFilter是CoreImage中提供的图像过滤器，也可以将其理解为滤镜。许多美颜应用，图像处理应用等都是为原图添加了滤镜效果。本节我们着重看下与这个类相关的应用。首先，CoreImaghe默认提供了非常多的滤镜效果，但是并没有详细的文档介绍，有关滤镜效果可以分为下面几个类别：

//通过改变图像的几何形状来创建3D效果，类似隆起 过滤器组
NSString * const kCICategoryDistortionEffect;
//旋转扭曲相关过滤器组
NSString * const kCICategoryGeometryAdjustment;
//混合过滤器组 对两个图像进行混合操作
NSString * const kCICategoryCompositeOperation;
//一种色调过滤器组 类似报纸风格
NSString * const kCICategoryHalftoneEffect;
//颜色过滤器组 调整对比度 亮度等
NSString * const kCICategoryColorEffect;
//多个图像源的过滤器
NSString * const kCICategoryTransition;
//平铺图像过滤器
NSString * const kCICategoryTileEffect;
//滤光类过滤器 通常作为其他过滤器的输入
NSString * const kCICategoryGenerator;
//减弱图像数据的过滤器 通常用来进行图像分析
NSString * const kCICategoryReduction;
//渐变过滤器
NSString * const kCICategoryGradient;
//画像过滤器
NSString * const kCICategoryStylize;
//锐化过滤器
NSString * const kCICategorySharpen;
//模糊过滤器
NSString * const kCICategoryBlur;
//视频图片相关过滤器
NSString * const kCICategoryVideo;
//静态图片相关过滤器
NSString * const kCICategoryStillImage;
//交叉图像过滤器
NSString * const kCICategoryInterlaced;
//非矩形图像上的过滤器
NSString * const kCICategoryNonSquarePixels;
//高动态图像的过滤器
NSString * const kCICategoryHighDynamicRange;
//CoreImage内置的过滤器
NSString * const kCICategoryBuiltIn;
//复合的过滤器
NSString * const kCICategoryFilterGenerator;

上面列出了非常多的类别，其实上面只是按照不同的场景将过滤器进行了分类，每个分类中都定义了许多内置的过滤器，使用下面的方法可以获取每个分类下提供的过滤器：

//获取某个分类的所有过滤器名
+ (NSArray<NSString *> *)filterNamesInCategory:(nullable NSString *)category;
//获取一组分类下的所有过滤器名
+ (NSArray<NSString *> *)filterNamesInCategories:(nullable NSArray<NSString *> *)categories;

2.过滤器的一个简单示例

下面示例代码演示过滤器的简单应用：

UIImage * img = [UIImage imageNamed:@"1.png"];
CIImage * image = [[CIImage alloc]initWithImage:img];
CIFilter * filter = [CIFilter filterWithName:@"CIBoxBlur" keysAndValues:kCIInputImageKey,image, nil];
[filter setDefaults];
CIContext * context = [[CIContext alloc]initWithOptions:nil];
CIImage * output = [filter outputImage];
CGImageRef ref = [context createCGImage:output fromRect:[output extent]];
UIImage * newImage = [UIImage imageWithCGImage:ref];
CGImageRelease(ref);
UIImageView * imageView = [[UIImageView alloc]initWithFrame:CGRectMake(170, 30, 150, 400)];
imageView.image = newImage;
[self.view addSubview:imageView];
UIImageView * imageView2 = [[UIImageView alloc]initWithFrame:CGRectMake(0, 30, 150, 400)];
imageView2.image = img;
[self.view addSubview:imageView2];

效果如下图：

上面演示了简单的模糊过滤效果。

3.对CIFilter类进行解析

CIFilter类的解析如下：

//过滤后输出的图像
@property (readonly, nonatomic, nullable) CIImage *outputImage;
//过滤器名称
@property (nonatomic, copy) NSString *name;
//是否开启CoreAnimation动画效果
@property (getter=isEnabled) BOOL enabled;
//返回当前过滤器所有支持的输入键
@property (nonatomic, readonly) NSArray<NSString *> *inputKeys;
//返回当前过滤器所有支持的输出键
@property (nonatomic, readonly) NSArray<NSString *> *outputKeys;
//将过滤器的所有输入值设置为默认值
- (void)setDefaults;
//返回当前过滤器的属性字段
/*
需要注意这个字段对于学习此过滤器非常有用
其中会声明此过滤器的输入和输出 即如果使用
*/
@property (nonatomic, readonly) NSDictionary<NSString *,id> *attributes;
//用来进行过滤器的自定义 后面会介绍
- (nullable CIImage *)apply:(CIKernel *)k
                  arguments:(nullable NSArray *)args
                    options:(nullable NSDictionary<NSString *,id> *)dict;
//同上
- (nullable CIImage *)apply:(CIKernel *)k, ...;
//根据过滤器的名称创建过滤器
+ (nullable CIFilter *) filterWithName:(NSString *) name;
//创建过滤器 同时进行配置
+ (nullable CIFilter *)filterWithName:(NSString *)name
                        keysAndValues:key0, ...;
+ (nullable CIFilter *)filterWithName:(NSString *)name
                  withInputParameters:(nullable NSDictionary<NSString *,id> *)params;
//注册过滤器
+ (void)registerFilterName:(NSString *)name
               constructor:(id<CIFilterConstructor>)anObject
           classAttributes:(NSDictionary<NSString *,id> *)attributes;
//将一组过滤器进行编码
+ (nullable NSData*)serializedXMPFromFilters:(NSArray<CIFilter *> *)filters
                            inputImageExtent:(CGRect)extent;
//进行反编码
+ (NSArray<CIFilter *> *)filterArrayFromSerializedXMP:(NSData *)xmpData
                                     inputImageExtent:(CGRect)extent
                                                error:(NSError **)outError;

4.常用过滤器详解

• 区域凸起过滤器

这个过滤器的作用是在图片的某个区域创建一块凸起。示例代码如下：

/*
kCIInputCenterKey键用来设置滤镜中心
kCIInputScaleKey 设置为0则没有影响 1则会凸起效果 -1则会凹入效果
kCIInputRadiusKey 设置滤镜的影响范围
*/
CIFilter * filter = [CIFilter filterWithName:@"CIBumpDistortion" keysAndValues:kCIInputImageKey,image,kCIInputCenterKey,[[CIVector alloc] initWithX:100 Y:200],kCIInputScaleKey,@-1,kCIInputRadiusKey,@150, nil];

效果如下：

 

• 线性凹凸过滤器

这个过滤器创建类似波纹效果，示例如下：

/*
与上一个过滤器相比 可以设置
kCIInputAngleKey 角度 0-2π
*/
CIFilter * filter = [CIFilter filterWithName:@"CIBumpDistortionLinear" keysAndValues:kCIInputImageKey,image,kCIInputCenterKey,[[CIVector alloc] initWithX:100 Y:200],kCIInputScaleKey,@-1,kCIInputRadiusKey,@150,kCIInputAngleKey,@(M_PI_2), nil];

效果如下：

 

• 圆形飞溅过滤器

这个过滤器的作用是选取图像的某个区域，对其四周进行飞溅拉伸，例如：

CIFilter * filter = [CIFilter filterWithName:@"CICircleSplashDistortion" keysAndValues:kCIInputImageKey,image,kCIInputCenterKey,[[CIVector alloc] initWithX:100 Y:200],kCIInputRadiusKey,@50, nil];

效果如下：

 

• 圆形缠绕过滤器

这个过滤器选取某个区域，进行缠绕效果，例如：

CIFilter * filter = [CIFilter filterWithName:@"CICircularWrap" keysAndValues:kCIInputImageKey,image,kCIInputCenterKey,[[CIVector alloc] initWithX:100 Y:200],kCIInputRadiusKey,@20, kCIInputAngleKey,@3,nil];

效果如下：

• 灰度混合过滤器

这个过滤器将提供混合图像的灰度值应用于目标图像，例如：

/*
inputDisplacementImage设置要混合的灰度图片
*/
CIFilter * filter = [CIFilter filterWithName:@"CIDroste" keysAndValues:kCIInputImageKey,image,kCIInputScaleKey,@200,@"inputDisplacementImage",image2,nil];

效果如下：

 

image

• 递归绘制图像区域

CIFilter * filter = [CIFilter filterWithName:@"CIDroste" keysAndValues:kCIInputImageKey,image,@"inputInsetPoint0",[[CIVector alloc] initWithX:100 Y:100],@"inputInsetPoint1",[[CIVector alloc] initWithX:200 Y:200],@"inputPeriodicity",@1,@"inputRotation",@0,@"inputStrands",@1,@"inputZoom",@1,nil];

效果如下：

 

image

• 玻璃纹理过滤器

这个过滤器用提供图片作为目标图片的纹理，进行混合，例如：

/*
inputTexture设置纹理图像
*/
CIFilter * filter = [CIFilter filterWithName:@"CIGlassDistortion" keysAndValues:kCIInputImageKey,image,kCIInputCenterKey,[[CIVector alloc] initWithX:100 Y:200],kCIInputScaleKey,@100,@"inputTexture",image2,nil];

效果如下：

 

image

• 菱形透镜过滤器

/*
inputPoint0设置第一个圆的圆心
inputPoint1设置第二个圆的圆心
inputRadius设置半径
inputRefraction设置折射率 0-5之间
*/
CIFilter * filter = [CIFilter filterWithName:@"CIGlassLozenge" keysAndValues:kCIInputImageKey,image,@"inputPoint0",[[CIVector alloc] initWithX:100 Y:200],@"inputPoint1",[[CIVector alloc] initWithX:200 Y:200],@"inputRadius",@100,@"inputRefraction",@2,nil];

效果如下：

 

image

• 圆孔形变过滤器

CIFilter * filter = [CIFilter filterWithName:@"CIHoleDistortion" keysAndValues:kCIInputImageKey,image,@"inputRadius",@50,kCIInputCenterKey,[[CIVector alloc] initWithX:100 Y:200],nil];

效果如下：

 

image

• 九宫格拉伸过滤器

CIFilter * filter = [CIFilter filterWithName:@"CINinePartStretched" keysAndValues:kCIInputImageKey,image2,@"inputBreakpoint0",[[CIVector alloc] initWithX:50 Y:50],@"inputBreakpoint1",[[CIVector alloc] initWithX:100 Y:100],@"inputGrowAmount",[[CIVector alloc] initWithX:50 Y:50],nil];

效果如下：

 

image

• 九宫格复制过滤器

CIFilter * filter = [CIFilter filterWithName:@"CINinePartTiled" keysAndValues:kCIInputImageKey,image2,@"inputBreakpoint0",[[CIVector alloc] initWithX:50 Y:50],@"inputBreakpoint1",[[CIVector alloc] initWithX:100 Y:100],@"inputGrowAmount",[[CIVector alloc] initWithX:50 Y:50],@"inputFlipYTiles",@1,nil];

效果如下：

 

image

• 紧缩过滤器

CIFilter * filter = [CIFilter filterWithName:@"CIPinchDistortion" keysAndValues:kCIInputImageKey,image2,@"inputCenter",[[CIVector alloc] initWithX:150 Y:150],@"inputRadius",@500,@"inputScale",@1,nil];

效果如下：

 

image

• 拉伸裁剪过滤器

/*
inputSize 设置拉伸裁剪尺寸
*/
CIFilter * filter = [CIFilter filterWithName:@"CIStretchCrop" keysAndValues:kCIInputImageKey,image2,@"inputCenterStretchAmount",@1,@"inputCropAmount",@0.5,@"inputSize",[[CIVector alloc] initWithX:300 Y:150],nil];

效果如下：

 

image

• 环状透镜过滤器

这个过滤器创建一个环状透镜，对图像进行扭曲。

/*
inputCenter设置环中心
inputRadius 设置半径
inputRefraction 设置折射率
inputWidth 设置环宽度
*/
CIFilter * filter = [CIFilter filterWithName:@"CITorusLensDistortion" keysAndValues:kCIInputImageKey,image2,@"inputCenter",[[CIVector alloc] initWithX:150 Y:150],@"inputRadius",@150,@"inputRefraction",@1.6,@"inputWidth",@40,nil];

效果如下：

 

image

• 旋转过滤器

CIFilter * filter = [CIFilter filterWithName:@"CITwirlDistortion" keysAndValues:kCIInputImageKey,image2,@"inputAngle",@3.14,@"inputCenter",[[CIVector alloc] initWithX:150 Y:150],@"inputRadius",@150,nil];

效果如下：

 

image

• 涡流过滤器

//inputAngle 设置涡流角度
CIFilter * filter = [CIFilter filterWithName:@"CIVortexDistortion" keysAndValues:kCIInputImageKey,image2,@"inputAngle",@(M_PI*10),@"inputCenter",[[CIVector alloc] initWithX:150 Y:150],@"inputRadius",@150,nil];

效果如下：

 

image

• 形变过滤器

这个过滤器对图像进行简单的形变处理，如缩放，旋转，平移等。

CGAffineTransform tr =  CGAffineTransformMakeRotation(M_PI_2);
CIFilter * filter = [CIFilter filterWithName:@"CIAffineTransform" keysAndValues:kCIInputImageKey,image2,@"inputTransform",[NSValue valueWithCGAffineTransform:tr],nil];

效果如下：

 

image

• 矩形裁剪过滤器

CIFilter * filter = [CIFilter filterWithName:@"CICrop" keysAndValues:kCIInputImageKey,image2,@"inputRectangle",[[CIVector alloc] initWithCGRect:CGRectMake(0, 0, 150, 150)],nil];

效果如下：

 

image

• 边缘采样过滤器

CIFilter * filter = [CIFilter filterWithName:@"CIEdgePreserveUpsampleFilter" keysAndValues:kCIInputImageKey,image,@"inputLumaSigma",@0.15,@"inputSpatialSigma",@3,@"inputSmallImage",image2,nil];

效果如下：

 

image

• 矩形矫正过滤器

CIFilter * filter = [CIFilter filterWithName:@"CIPerspectiveCorrection" keysAndValues:kCIInputImageKey,image2,@"inputBottomLeft",[[CIVector alloc] initWithX:0 Y:0],@"inputBottomRight",[[CIVector alloc] initWithX:150 Y:0],@"inputTopLeft",[[CIVector alloc] initWithX:0 Y:150],@"inputTopRight",[[CIVector alloc] initWithX:150 Y:150],nil];

效果如图：

 

image

• 旋转矫正过滤器

CIFilter * filter = [CIFilter filterWithName:@"CIStraightenFilter" keysAndValues:kCIInputImageKey,image2,@"inputAngle",@3.14,nil];

效果如下：

 

image

• 背景混合过滤器

通过提供一个图像作为背景与目标图像进行混合。

CIFilter * filter = [CIFilter filterWithName:@"CIAdditionCompositing" keysAndValues:kCIInputImageKey,image2,@"inputBackgroundImage",image,nil];

效果如下：

 

image

• 色彩混合过滤器

CIFilter * filter = [CIFilter filterWithName:@"CIColorBlendMode" keysAndValues:kCIInputImageKey,image2,@"inputBackgroundImage",image,nil];

效果如下：

 

image

• 暗混合过滤器

CIFilter * filter = [CIFilter filterWithName:@"CIColorBurnBlendMode" keysAndValues:kCIInputImageKey,image2,@"inputBackgroundImage",image,nil];

效果如下：

 

image

• 亮混合过滤器

CIFilter * filter = [CIFilter filterWithName:@"CIColorDodgeBlendMode" keysAndValues:kCIInputImageKey,image2,@"inputBackgroundImage",image,nil];

 

image

• 暗选择混合模式过滤器

这个过滤器将选择较暗的图像作为混合背景，例如：

CIFilter * filter = [CIFilter filterWithName:@"CIDarkenBlendMode" keysAndValues:kCIInputImageKey,image2,@"inputBackgroundImage",image,nil];

效果如下：

 

image

• 亮选择混合模式过滤器

这个过滤器将选择较亮的图像作为混合背景，例如：

CIFilter * filter = [CIFilter filterWithName:@"CIDifferenceBlendMode" keysAndValues:kCIInputImageKey,image2,@"inputBackgroundImage",image,nil];

效果如下：

 

image

• 分开混合模式过滤器

CIFilter * filter = [CIFilter filterWithName:@"CIDivideBlendMode" keysAndValues:kCIInputImageKey,image2,@"inputBackgroundImage",image,nil];

效果如下：

 

image

• 排除混合模式过滤器

CIFilter * filter = [CIFilter filterWithName:@"CIExclusionBlendMode" keysAndValues:kCIInputImageKey,image2,@"inputBackgroundImage",image,nil];

效果如下：

 

image

• 强光混合模式过滤器

CIFilter * filter = [CIFilter filterWithName:@"CIHardLightBlendMode" keysAndValues:kCIInputImageKey,image2,@"inputBackgroundImage",image,nil];

效果如下：

 

image

• 色调混合模式过滤器

CIFilter * filter = [CIFilter filterWithName:@"CIHueBlendMode" keysAndValues:kCIInputImageKey,image2,@"inputBackgroundImage",image,nil];

效果如下：

 

image

• 减轻混合模式过滤器

CIFilter * filter = [CIFilter filterWithName:@"CILightenBlendMode" keysAndValues:kCIInputImageKey,image2,@"inputBackgroundImage",image,nil];

效果如下：

 

image

• 线性燃烧混合模式过滤器

CIFilter * filter = [CIFilter filterWithName:@"CILinearBurnBlendMode" keysAndValues:kCIInputImageKey,image2,@"inputBackgroundImage",image,nil];

效果如下：

 

image

• 线性高亮混合过滤器

CIFilter * filter = [CIFilter filterWithName:@"CILinearDodgeBlendMode" keysAndValues:kCIInputImageKey,image2,@"inputBackgroundImage",image,nil];

效果如下：

 

image

• 亮度混合过滤器

CIFilter * filter = [CIFilter filterWithName:@"CILuminosityBlendMode" keysAndValues:kCIInputImageKey,image2,@"inputBackgroundImage",image,nil];

效果如下：

 

image

• 最大值混合过滤器

CIFilter * filter = [CIFilter filterWithName:@"CIMaximumCompositing" keysAndValues:kCIInputImageKey,image2,@"inputBackgroundImage",image,nil];

效果如下：

 

image

• 最小值混合过滤器

CIFilter * filter = [CIFilter filterWithName:@"CIMinimumCompositing" keysAndValues:kCIInputImageKey,image2,@"inputBackgroundImage",image,nil];

效果如下：

 

image

• 多重混合过滤器

CIFilter * filter = [CIFilter filterWithName:@"CIMultiplyBlendMode" keysAndValues:kCIInputImageKey,image2,@"inputBackgroundImage",image,nil];

效果如下：

 

image

• 多重合成过滤器

CIFilter * filter = [CIFilter filterWithName:@"CIMultiplyCompositing" keysAndValues:kCIInputImageKey,image2,@"inputBackgroundImage",image,nil];

 

image

• 重叠混合模式

CIFilter * filter = [CIFilter filterWithName:@"CIOverlayBlendMode" keysAndValues:kCIInputImageKey,image2,@"inputBackgroundImage",image,nil];

 

image

• 亮混合模式

CIFilter * filter = [CIFilter filterWithName:@"CIPinLightBlendMode" keysAndValues:kCIInputImageKey,image2,@"inputBackgroundImage",image,nil];

 

image

• 饱和混合模式

CIFilter * filter = [CIFilter filterWithName:@"CISaturationBlendMode" keysAndValues:kCIInputImageKey,image2,@"inputBackgroundImage",image,nil];

 

image

• 屏幕混合模式

CIFilter * filter = [CIFilter filterWithName:@"CIScreenBlendMode" keysAndValues:kCIInputImageKey,image2,@"inputBackgroundImage",image,nil];

 

image

• 源图像上层混合

CIFilter * filter = [CIFilter filterWithName:@"CISourceAtopCompositing" keysAndValues:kCIInputImageKey,image2,@"inputBackgroundImage",image,nil];

 

image

• 圆屏过滤器

/*
inputSharpness 设置圆圈锐度
inputWidth 设置间距
*/
CIFilter * filter = [CIFilter filterWithName:@"CICircularScreen" keysAndValues:kCIInputImageKey,image2,kCIInputCenterKey,[[CIVector alloc] initWithX:150 Y:150],@"inputSharpness",@0.7,@"inputWidth",@6,nil];

 

image

• 半色调过滤器

CIFilter * filter = [CIFilter filterWithName:@"CICMYKHalftone" keysAndValues:kCIInputImageKey,image2,@"inputAngle",@0,kCIInputCenterKey,[[CIVector alloc] initWithX:150 Y:150],@"inputGCR",@1,@"inputSharpness",@0.7,@"inputUCR",@0.5,@"inputWidth",@6,nil];

 

image

• 点屏过滤器

CIFilter * filter = [CIFilter filterWithName:@"CIDotScreen" keysAndValues:kCIInputImageKey,image2,@"inputAngle",@0,kCIInputCenterKey,[[CIVector alloc] initWithX:150 Y:150],@"inputSharpness",@0.7,@"inputWidth",@6,nil];

 

image

• 阴影屏过滤器

CIFilter * filter = [CIFilter filterWithName:@"CIHatchedScreen" keysAndValues:kCIInputImageKey,image2,@"inputAngle",@0,kCIInputCenterKey,[[CIVector alloc] initWithX:150 Y:150],@"inputSharpness",@0.7,@"inputWidth",@6,nil];

 

image

• 线性sRGB过滤器

CIFilter * filter = [CIFilter filterWithName:@"CILinearToSRGBToneCurve" keysAndValues:kCIInputImageKey,image2,nil];

 

image

• 色彩翻转过滤器

CIFilter * filter = [CIFilter filterWithName:@"CIColorInvert" keysAndValues:kCIInputImageKey,image2,nil];

 

image

• 色图过滤器

CIFilter * filter = [CIFilter filterWithName:@"CIColorMap" keysAndValues:kCIInputImageKey,image2,@"inputGradientImage",image,nil];

 

image

• 单色过滤器

/*
inputColor 设置输入颜色
inputIntensity 设置影响程度
*/
CIFilter * filter = [CIFilter filterWithName:@"CIColorMonochrome" keysAndValues:kCIInputImageKey,image2,@"inputColor",[CIColor colorWithRed:0.5 green:0.5 blue:0.5],@"inputIntensity",@1,nil];

 

image

• 分色镜过滤器

/*
inputLevels设置亮度级别
*/
CIFilter * filter = [CIFilter filterWithName:@"CIColorPosterize" keysAndValues:kCIInputImageKey,image2,@"inputLevels",@6,nil];

 

image

• 反色过滤器

CIFilter * filter = [CIFilter filterWithName:@"CIFalseColor" keysAndValues:kCIInputImageKey,image2,@"inputColor0",[CIColor colorWithRed:0 green:0 blue:0],@"inputColor1",[CIColor colorWithRed:1 green:1 blue:0],nil];

 

image

• 光效褪色过滤器

CIFilter * filter = [CIFilter filterWithName:@"CIPhotoEffectFade" keysAndValues:kCIInputImageKey,image2,nil];

 

image

• 光效瞬时过滤器

CIFilter * filter = [CIFilter filterWithName:@"CIPhotoEffectInstant" keysAndValues:kCIInputImageKey,image2,nil];

 

image

• 光效单光过滤器

CIFilter * filter = [CIFilter filterWithName:@"CIPhotoEffectMono" keysAndValues:kCIInputImageKey,image2,nil];

 

image

• 黑色光效应过滤器

CIFilter * filter = [CIFilter filterWithName:@"CIPhotoEffectNoir" keysAndValues:kCIInputImageKey,image2,nil];

 

image

• 光渐进过滤器

CIFilter * filter = [CIFilter filterWithName:@"CIPhotoEffectProcess" keysAndValues:kCIInputImageKey,image2,nil];

 

image

• 光转移过滤器

CIFilter * filter = [CIFilter filterWithName:@"CIPhotoEffectTransfer" keysAndValues:kCIInputImageKey,image2,nil];

 

image

• 棕褐色过滤器

CIFilter * filter = [CIFilter filterWithName:@"CISepiaTone" keysAndValues:kCIInputImageKey,image2,nil];

 

image

• 热图过滤器

CIFilter * filter = [CIFilter filterWithName:@"CIThermal" keysAndValues:kCIInputImageKey,image2,nil];

 

image

• X射线过滤器

CIFilter * filter = [CIFilter filterWithName:@"CIXRay" keysAndValues:kCIInputImageKey,image2,nil];

 

image

• 模糊过滤器

//参数进行模糊效果的设置
CIFilter * filter = [CIFilter filterWithName:@"CIBokehBlur" keysAndValues:kCIInputImageKey,image2,@"inputSoftness",@0.5,@"inputRingSize",@0.1,@"inputRingAmount",@0,@"inputRadius",@10,nil];

 

image

• 盒模糊过滤器

CIFilter * filter = [CIFilter filterWithName:@"CIBoxBlur" keysAndValues:kCIInputImageKey,image2,@"inputRadius",@10,nil];

 

image

• 阀瓣模糊过滤器

CIFilter * filter = [CIFilter filterWithName:@"CIDiscBlur" keysAndValues:kCIInputImageKey,image2,@"inputRadius",@25,nil];

 

image

• 高斯模糊过滤器

CIFilter * filter = [CIFilter filterWithName:@"CIGaussianBlur" keysAndValues:kCIInputImageKey,image2,@"inputRadius",@10,nil];

 

image

• 梯度模糊过滤器

CIFilter * filter = [CIFilter filterWithName:@"CIMorphologyGradient" keysAndValues:kCIInputImageKey,image2,@"inputRadius",@5,nil];

 

image

• 运动模糊过滤器

CIFilter * filter = [CIFilter filterWithName:@"CIMotionBlur" keysAndValues:kCIInputImageKey,image2,@"inputRadius",@5,nil];

 

image

• 缩放模糊过滤器

CIFilter * filter = [CIFilter filterWithName:@"CIZoomBlur" keysAndValues:kCIInputImageKey,image2,nil];

 

image

5.自定义过滤器

上面演示了非常多的常用内置过滤器，我们也可以通过继承CIFilter来自定义过滤器。

自定义过滤器之前，首先需要了解CIKernel这个类，CIKernel是Core Image Kernel Language 的抽象对象。CIKL是CoreImage中专门用来编写像素处理函数的语言。

CIKernel相关类解析如下：

//基类 用于通用的过滤函数
@interface CIKernel : NSObject
//从字符串加载一组过滤函数
+ (nullable NSArray<CIKernel *> *)kernelsWithString:(NSString *)string;
//从字符串加载一个过滤函数
+ (nullable instancetype)kernelWithString:(NSString *)string ;
//名称
@property (atomic, readonly) NSString *name ;
//进行图片生成
- (nullable CIImage *)applyWithExtent:(CGRect)extent
                          roiCallback:(CIKernelROICallback)callback
                            arguments:(nullable NSArray<id> *)args;
@end
//用于颜色修正的过滤函数
@interface CIColorKernel : CIKernel
+ (nullable instancetype)kernelWithString:(NSString *)string;
- (nullable CIImage *)applyWithExtent:(CGRect)extent
                            arguments:(nullable NSArray<id> *)args;
@end
//用于形状修正的过滤函数
@interface CIWarpKernel : CIKernel
+ (nullable instancetype)kernelWithString:(NSString *)string;
@end
//用于色彩混合的过滤函数
@interface CIBlendKernel : CIColorKernel
+ (nullable instancetype)kernelWithString:(NSString *)string;
- (nullable CIImage *)applyWithForeground:(CIImage*)foreground
                               background:(CIImage*)background;
@end

下面是一个简单的翻转图像的自定义过滤器示意，首先新建一个新的cikernel文件，命名为a.cikernel，如下：

kernel vec2 mirrorX ( float imageWidth )
{
// 获取待处理点的位置
vec2 currentVec = destCoord();
// 返回最终显示位置
return vec2 ( imageWidth - currentVec.x , currentVec.y );
}

新建一个过滤器类，命名为MyFilter，如下：

#import <CoreImage/CoreImage.h>
@interface MyFilter : CIFilter
@property(nonatomic,strong)CIImage * inputImage;
@end
#import "MyFilter.h"

@interface MyFilter()

@property(nonatomic,strong)CIWarpKernel * kernel;

@end

@implementation MyFilter

- (instancetype)init {

    self = [super init];
    if (self) {
            //从文件读取过滤函数
            NSBundle *bundle = [NSBundle bundleForClass: [self class]];
            NSURL *kernelURL = [bundle URLForResource:@"a" withExtension:@"cikernel"];
            NSError *error;
            NSString *kernelCode = [NSString stringWithContentsOfURL:kernelURL
                                                            encoding:NSUTF8StringEncoding error:&error];

            NSArray *kernels = [CIKernel kernelsWithString:kernelCode];
            self.kernel = [kernels objectAtIndex:0];
    }
    return self;
}

- (CIImage *)outputImage
{
    CGFloat inputWidth = self.inputImage.extent.size.width;
    CIImage *result = [self.kernel applyWithExtent:self.inputImage.extent roiCallback:^CGRect(int index, CGRect destRect) {
        return destRect;
    } inputImage:self.inputImage arguments:@[@(inputWidth)]];
    return result;
}
//设置说明字典
-(NSDictionary<NSString *,id> *)attributes{
    return @{
             @"inputImage" :  @{
                 @"CIAttributeClass" : @"CIImage",
                 @"CIAttributeDisplayName" : @"Image--",
                 @"CIAttributeType" : @"CIAttributeTypeImage"
                 }};
}
@end

如下进行使用即可：

MyFilter * filter = [[MyFilter alloc]init];
filter.inputImage = image2;
CIContext * context = [[CIContext alloc]initWithOptions:nil];
CIImage * output = [filter outputImage];
CGImageRef ref = [context createCGImage:output fromRect:output.extent];
UIImage * newImage = [UIImage imageWithCGImage:ref];

 

 

二、使用CoreImage实现人脸识别

人脸识别是目前非常热门的一种图像处理技术，CoreImage内置了对人脸进行识别的相关功能接口，并且可以对人脸面部特征进行抓取，下面我们来实现一个简单的实时识别人脸特征的Demo。

首先创建一个视图作为图像扫描视图，如下：

.h文件

//.h 文件
@interface FaceView : UIView
@end

.m文件

//
//  FaceView.m
//  CoreImageDemo
//
//  Created by jaki on 2018/12/22.
//  Copyright © 2018年 jaki. All rights reserved.
//

#import "FaceView.h"
#import <AVFoundation/AVFoundation.h>
#import "FaceHandle.h"
//定义线程
#define FACE_SCAN_QUEUE "FACE_SCAN_QUEUE"

@interface FaceView()<AVCaptureVideoDataOutputSampleBufferDelegate>

@property(nonatomic,strong)AVCaptureSession *captureSession;

@property(nonatomic,strong)AVCaptureDeviceInput * captureInput;

@property(nonatomic,strong)AVCaptureVideoDataOutput * captureOutput;

@property(nonnull,strong)AVCaptureVideoPreviewLayer * videoLayer;

@property(nonatomic,strong)dispatch_queue_t queue;

@property(nonatomic,assign)BOOL hasHandle;

@property(nonatomic,strong)UIView * faceView;

@end

@implementation FaceView
#pragma mark - Override
-(instancetype)init{
    self = [super init];
    if (self) {
        [self install];
    }
    return self;
}

-(instancetype)initWithFrame:(CGRect)frame{
    self = [super initWithFrame:frame];
    if (self) {
        [self install];
    }
    return self;
}
-(void)layoutSubviews{
    [super layoutSubviews];
    self.videoLayer.frame = self.bounds;
}

#pragma mark - InnerFunc
-(void)install{
    if (![UIImagePickerController isSourceTypeAvailable:UIImagePickerControllerSourceTypeCamera]) {
        NSLog(@"不支持");
        return;
    }
    self.queue = dispatch_queue_create(FACE_SCAN_QUEUE, NULL);
    [self.captureSession startRunning];
    AVAuthorizationStatus status = [AVCaptureDevice authorizationStatusForMediaType:AVMediaTypeVideo];
    if (status!=AVAuthorizationStatusAuthorized) {
        NSLog(@"需要权限");
        return;
    }
    self.videoLayer = [AVCaptureVideoPreviewLayer layerWithSession:self.captureSession];
    self.videoLayer.frame = CGRectZero;
    self.videoLayer.videoGravity = AVLayerVideoGravityResizeAspectFill;
    [self.layer addSublayer:self.videoLayer];
    [self addSubview:self.faceView];
    self.faceView.frame = CGRectMake(0, 0, self.frame.size.width, self.frame.size.height);

}
//将人脸特征点标记出来
-(void)renderReactWithInfo:(NSDictionary *)info{
    for (UIView * v in self.faceView.subviews) {
        [v removeFromSuperview];
    }
    NSArray * faceArray = info[FACE_HANDLE_INFO_FACE_ARRAY];
    for (int i = 0;i < faceArray.count; i++) {
        NSDictionary * face = faceArray[i];
        NSValue * faceValue = face[FACE_HANDLE_INFO_FACE_FRAME];
        if (faceValue) {
            CGRect faceR = [faceValue CGRectValue];
            UIView * faceView = [[UIView alloc]initWithFrame:faceR];
            faceView.backgroundColor = [UIColor clearColor];
            faceView.layer.borderColor = [UIColor redColor].CGColor;
            faceView.layer.borderWidth = 2;
            [self.faceView addSubview:faceView];
        }
        NSValue * leftEye = face[FACE_HANDLE_INFO_FACE_LEFT_EYE_FRAME];
        if (leftEye) {
            CGRect leftEyeR = [leftEye CGRectValue];
            UIView * eye = [[UIView alloc]initWithFrame:leftEyeR];
            eye.backgroundColor = [UIColor clearColor];
            eye.layer.borderColor = [UIColor greenColor].CGColor;
            eye.layer.borderWidth = 2;
            [self.faceView addSubview:eye];
        }
        NSValue * rightEye = face[FACE_HANDLE_INFO_FACE_RIGHT_EYE_FRAME];
        if (rightEye) {
            CGRect rightEyeR = [rightEye CGRectValue];
            UIView * eye = [[UIView alloc]initWithFrame:rightEyeR];
            eye.backgroundColor = [UIColor clearColor];
            eye.layer.borderColor = [UIColor greenColor].CGColor;
            eye.layer.borderWidth = 2;
            [self.faceView addSubview:eye];
        }
        NSValue * mouth = face[FACE_HANDLE_INFO_FACE_MOUTH_FRAME];
        if (mouth) {
            CGRect mouthR = [mouth CGRectValue];
            UIView * mouth = [[UIView alloc]initWithFrame:mouthR];
            mouth.backgroundColor = [UIColor clearColor];
            mouth.layer.borderColor = [UIColor orangeColor].CGColor;
            mouth.layer.borderWidth = 2;
            [self.faceView addSubview:mouth];
        }
    }
}

#pragma AVDelegate
//进行画面的捕获
-(void)captureOutput:(AVCaptureOutput *)output didOutputSampleBuffer:(CMSampleBufferRef)sampleBuffer fromConnection:(AVCaptureConnection *)connection{
    if (self.hasHandle) {
        return;
    }
    self.hasHandle = YES;
    CVImageBufferRef imageBuffer = CMSampleBufferGetImageBuffer(sampleBuffer);
    CVPixelBufferLockBaseAddress(imageBuffer,0);
    uint8_t *baseAddress = (uint8_t *)CVPixelBufferGetBaseAddress(imageBuffer);
    size_t bytesPerRow = CVPixelBufferGetBytesPerRow(imageBuffer);
    size_t width = CVPixelBufferGetWidth(imageBuffer);
    size_t height = CVPixelBufferGetHeight(imageBuffer);

    CGColorSpaceRef colorSpace = CGColorSpaceCreateDeviceRGB();
    CGContextRef newContext = CGBitmapContextCreate(baseAddress,width, height, 8, bytesPerRow, colorSpace,kCGBitmapByteOrder32Little | kCGImageAlphaPremultipliedFirst);
    CGImageRef newImage = CGBitmapContextCreateImage(newContext);
    CGContextRelease(newContext);
    CGColorSpaceRelease(colorSpace);
    UIImage *image= [UIImage imageWithCGImage:newImage scale:1.0 orientation:UIImageOrientationRight];
    CGImageRelease(newImage);
    //image
     //进行人脸识别的核心工具类
    [[FaceHandle sharedInstance] handleImage:image viewSize:self.frame.size completed:^(BOOL success, NSDictionary *info) {
        self.hasHandle  = NO;
        [self renderReactWithInfo:info];
    }];

    CVPixelBufferUnlockBaseAddress(imageBuffer,0);
}

#pragma mark - setter and getter

-(AVCaptureSession *)captureSession{
    if (!_captureSession) {
        _captureSession = [[AVCaptureSession alloc]init];
        [_captureSession addInput:self.captureInput];
        [_captureSession addOutput:self.captureOutput];
    }
    return _captureSession;
}

-(AVCaptureDeviceInput *)captureInput{
    if (!_captureInput) {
        _captureInput = [AVCaptureDeviceInput deviceInputWithDevice:[AVCaptureDevice defaultDeviceWithMediaType:AVMediaTypeVideo] error:nil];
    }
    return _captureInput;
}

-(AVCaptureVideoDataOutput *)captureOutput{
    if (!_captureOutput) {
        _captureOutput = [[AVCaptureVideoDataOutput alloc]init];
        _captureOutput.alwaysDiscardsLateVideoFrames = YES;
        [_captureOutput setSampleBufferDelegate:self queue:self.queue];
        _captureOutput.videoSettings = @{(__bridge NSString *)kCVPixelBufferPixelFormatTypeKey:@(kCVPixelFormatType_32BGRA)};
    }
    return _captureOutput;
}

-(UIView *)faceView{
    if (!_faceView) {
        _faceView = [[UIView alloc]init];
        _faceView.backgroundColor = [UIColor clearColor];
    }
    return _faceView;
}

@end

在真机上运行工程，通过摄像头可以将实时的画面捕获到屏幕上，下面实现核心的人脸识别代码：

创建继承于NSObject的FaceHandle类，如下：

.h文件

extern const NSString * FACE_HANDLE_INFO_FACE_ARRAY;

extern const NSString * FACE_HANDLE_INFO_FACE_FRAME;

extern const NSString * FACE_HANDLE_INFO_FACE_LEFT_EYE_FRAME;

extern const NSString * FACE_HANDLE_INFO_FACE_RIGHT_EYE_FRAME;

extern const NSString * FACE_HANDLE_INFO_FACE_MOUTH_FRAME;

extern const NSString * FACE_HANDLE_INFO_ERROR;
@interface FaceHandle : NSObject
+(instancetype)sharedInstance;

-(void)handleImage:(UIImage *)image viewSize:(CGSize )viewSize completed:(void(^)(BOOL  success,NSDictionary * info))completion;
@end

.m文件

#import "FaceHandle.h"
#define FACE_HANDLE_DISPATCH_QUEUE "FACE_HANDLE_DISPATCH_QUEUE"
const NSString * FACE_HANDLE_INFO_FACE_FRAME = @"FACE_HANDLE_INFO_FACE_FRAME";

const NSString * FACE_HANDLE_INFO_FACE_LEFT_EYE_FRAME = @"FACE_HANDLE_INFO_FACE_LEFT_EYE_FRAME";

const NSString * FACE_HANDLE_INFO_FACE_RIGHT_EYE_FRAME = @"FACE_HANDLE_INFO_FACE_RIGHT_EYE_FRAME";

const NSString * FACE_HANDLE_INFO_FACE_MOUTH_FRAME = @"FACE_HANDLE_INFO_FACE_MOUTH_FRAME";

const NSString * FACE_HANDLE_INFO_ERROR = @"FACE_HANDLE_INFO_ERROR";

const NSString * FACE_HANDLE_INFO_FACE_ARRAY = @"FACE_HANDLE_INFO_FACE_ARRAY";
@interface FaceHandle()

@property(nonatomic,strong)dispatch_queue_t workingQueue;

@end

@implementation FaceHandle

+(instancetype)sharedInstance{
    static dispatch_once_t onceToken;
    static FaceHandle * sharedInstance = nil;
    if (!sharedInstance) {
        dispatch_once(&onceToken, ^{
            sharedInstance = [[FaceHandle alloc] init];
        });
    }
    return sharedInstance;
}

#pragma mark - Override
-(instancetype)init{
    self = [super init];
    if (self) {
        self.workingQueue = dispatch_queue_create(FACE_HANDLE_DISPATCH_QUEUE, NULL);
    }
    return self;
}

#pragma mark - InnerFunc
-(void)handleImage:(UIImage *)image viewSize:(CGSize )viewSize completed:(void (^)(BOOL , NSDictionary *))completion{
    if (!image) {
        if (completion) {
            completion(NO,@{FACE_HANDLE_INFO_ERROR:@"图片捕获出错"});
        }
        return;
    }
    dispatch_async(self.workingQueue, ^{
        UIImage * newImage = [self strectImage:image withSize:viewSize];
        if (newImage) {
            NSArray * faceArray = [self analyseFaceImage:newImage];
            if (completion) {
                dispatch_async(dispatch_get_main_queue(), ^{
                    completion(YES,@{FACE_HANDLE_INFO_FACE_ARRAY:faceArray});
                });
            }
        }else{
            if (completion) {
                dispatch_async(dispatch_get_main_queue(), ^{
                    completion(NO,@{FACE_HANDLE_INFO_ERROR:@"图片识别出错"});
                });
            }
        }
    });
}

//图片放大处理
-(UIImage *)strectImage:(UIImage *)img withSize:(CGSize)size{
    UIGraphicsBeginImageContext(size);
    CGRect thumbnailRect = CGRectZero;
    thumbnailRect.origin = CGPointMake(0, 0);
    thumbnailRect.size.width  = size.width;
    thumbnailRect.size.height = size.height;
    [img drawInRect:thumbnailRect];
    UIImage * newImage = UIGraphicsGetImageFromCurrentImageContext();
    UIGraphicsEndImageContext();

    if (newImage) {
        return  newImage;
    }
    return nil;
}

-(NSArray *)analyseFaceImage:(UIImage *)image{
    NSMutableArray * dataArray = [NSMutableArray array];
    CIImage * cImage = [CIImage imageWithCGImage:image.CGImage];
    NSDictionary* opts = [NSDictionary dictionaryWithObject:
                          CIDetectorAccuracyHigh forKey:CIDetectorAccuracy];
    //进行分析
    CIDetector* detector = [CIDetector detectorOfType:CIDetectorTypeFace
                                              context:nil options:opts];
    //获取特征数组
    NSArray* features = [detector featuresInImage:cImage];
    CGSize inputImageSize = [cImage extent].size;
    CGAffineTransform  transform = CGAffineTransformIdentity;
    transform = CGAffineTransformScale(transform, 1, -1);
    transform = CGAffineTransformTranslate(transform, 0, -inputImageSize.height);

    for (CIFaceFeature *faceFeature in features){
        NSMutableDictionary * faceDic = [NSMutableDictionary dictionary];
        CGRect faceViewBounds = CGRectApplyAffineTransform(faceFeature.bounds, transform);
        [faceDic setValue:[NSValue valueWithCGRect:faceViewBounds] forKey:(NSString *)FACE_HANDLE_INFO_FACE_FRAME];
        CGFloat faceWidth = faceFeature.bounds.size.width;
        if(faceFeature.hasLeftEyePosition){
            CGPoint faceViewLeftPoint = CGPointApplyAffineTransform(faceFeature.leftEyePosition, transform);
            CGRect leftEyeBounds = CGRectMake(faceViewLeftPoint.x-faceWidth*0.1, faceViewLeftPoint.y-faceWidth*0.1, faceWidth*0.2, faceWidth*0.2);
            [faceDic setValue:[NSValue valueWithCGRect:leftEyeBounds] forKey:(NSString *)FACE_HANDLE_INFO_FACE_LEFT_EYE_FRAME];
        }

        if(faceFeature.hasRightEyePosition){
            //获取人右眼对应的point
            CGPoint faceViewRightPoint = CGPointApplyAffineTransform(faceFeature.rightEyePosition, transform);
            CGRect rightEyeBounds = CGRectMake(faceViewRightPoint.x-faceWidth*0.1, faceViewRightPoint.y-faceWidth*0.1, faceWidth*0.2, faceWidth*0.2);
            [faceDic setValue:[NSValue valueWithCGRect:rightEyeBounds] forKey:(NSString *)FACE_HANDLE_INFO_FACE_RIGHT_EYE_FRAME];
        }

        if(faceFeature.hasMouthPosition){
            //获取人嘴巴对应的point
            CGPoint faceViewMouthPoint = CGPointApplyAffineTransform(faceFeature.mouthPosition, transform);
            CGRect mouthBounds = CGRectMake(faceViewMouthPoint.x-faceWidth*0.2, faceViewMouthPoint.y-faceWidth*0.2, faceWidth*0.4, faceWidth*0.4);
            [faceDic setValue:[NSValue valueWithCGRect:mouthBounds] forKey:(NSString *)FACE_HANDLE_INFO_FACE_MOUTH_FRAME];
        }
        [dataArray addObject:faceDic];
    }
    return [dataArray copy];
}
@end

打开百度，随便搜索一些人脸图片进行识别，可以看到识别率还是很高，如下图：

 

image

三、CIImage中提供了其他图像识别功能

CIDetector除了可以用来进行人脸识别外，还支持进行二维码、矩形、文字等检测。

矩形区域识别，用来检测图像中的矩形边界，核心代码如下：

-(NSArray *)analyseRectImage:(UIImage *)image{
    NSMutableArray * dataArray = [NSMutableArray array];
    CIImage * cImage = [CIImage imageWithCGImage:image.CGImage];
    NSDictionary* opts = [NSDictionary dictionaryWithObject:
                          CIDetectorAccuracyHigh forKey:CIDetectorAccuracy];
    CIDetector* detector = [CIDetector detectorOfType:CIDetectorTypeRectangle
                                              context:nil options:opts];
    NSArray* features = [detector featuresInImage:cImage];
    CGSize inputImageSize = [cImage extent].size;
    CGAffineTransform  transform = CGAffineTransformIdentity;
    transform = CGAffineTransformScale(transform, 1, -1);
    transform = CGAffineTransformTranslate(transform, 0, -inputImageSize.height);

    for (CIRectangleFeature *feature in features){
        NSLog(@"%lu",features.count);
        NSMutableDictionary * dic = [NSMutableDictionary dictionary];
        CGRect viewBounds = CGRectApplyAffineTransform(feature.bounds, transform);
        [dic setValue:[NSValue valueWithCGRect:viewBounds] forKey:@"rectBounds"];
        CGPoint topLeft = CGPointApplyAffineTransform(feature.topLeft, transform);
        [dic setValue:[NSValue valueWithCGPoint:topLeft] forKey:@"topLeft"];
        CGPoint topRight = CGPointApplyAffineTransform(feature.topRight, transform);
        [dic setValue:[NSValue valueWithCGPoint:topRight] forKey:@"topRight"];
        CGPoint bottomLeft = CGPointApplyAffineTransform(feature.bottomLeft, transform);
        [dic setValue:[NSValue valueWithCGPoint:bottomLeft] forKey:@"bottomLeft"];
        CGPoint bottomRight = CGPointApplyAffineTransform(feature.bottomRight, transform);
        [dic setValue:[NSValue valueWithCGPoint:bottomRight] forKey:@"bottomRight"];
        [dataArray addObject:dic];
    }
    return [dataArray copy];
}

效果如下图所示：

 

image

二维码扫描不仅可以分析出图片中的二维码位置，还可以解析出二维码数据，核心代码如下：

-(NSArray *)analyseQRImage:(UIImage *)image{
    NSMutableArray * dataArray = [NSMutableArray array];
    CIImage * cImage = [CIImage imageWithCGImage:image.CGImage];
    NSDictionary* opts = [NSDictionary dictionaryWithObject:
                          CIDetectorAccuracyHigh forKey:CIDetectorAccuracy];
    CIDetector* detector = [CIDetector detectorOfType:CIDetectorTypeQRCode
                                              context:nil options:opts];
    NSArray* features = [detector featuresInImage:cImage];
    CGSize inputImageSize = [cImage extent].size;
    CGAffineTransform  transform = CGAffineTransformIdentity;
    transform = CGAffineTransformScale(transform, 1, -1);
    transform = CGAffineTransformTranslate(transform, 0, -inputImageSize.height);

    for (CIQRCodeFeature *feature in features){
        NSMutableDictionary * dic = [NSMutableDictionary dictionary];
        CGRect viewBounds = CGRectApplyAffineTransform(feature.bounds, transform);
        [dic setValue:[NSValue valueWithCGRect:viewBounds] forKey:@"rectBounds"];
        CGPoint topLeft = CGPointApplyAffineTransform(feature.topLeft, transform);
        [dic setValue:[NSValue valueWithCGPoint:topLeft] forKey:@"topLeft"];
        CGPoint topRight = CGPointApplyAffineTransform(feature.topRight, transform);
        [dic setValue:[NSValue valueWithCGPoint:topRight] forKey:@"topRight"];
        CGPoint bottomLeft = CGPointApplyAffineTransform(feature.bottomLeft, transform);
        [dic setValue:[NSValue valueWithCGPoint:bottomLeft] forKey:@"bottomLeft"];
        CGPoint bottomRight = CGPointApplyAffineTransform(feature.bottomRight, transform);
        [dic setValue:[NSValue valueWithCGPoint:bottomRight] forKey:@"bottomRight"];
        [dic setValue:feature.messageString forKey:@"content"];
        [dataArray addObject:dic];
    }
    return [dataArray copy];
}

CIImage框架中还支持对文本区域进行分析，核心代码如下：

-(NSArray *)analyseTextImage:(UIImage *)image{
    NSMutableArray * dataArray = [NSMutableArray array];
    CIImage * cImage = [CIImage imageWithCGImage:image.CGImage];
    NSDictionary* opts = [NSDictionary dictionaryWithObject:
                          CIDetectorAccuracyHigh forKey:CIDetectorAccuracy];
    CIDetector* detector = [CIDetector detectorOfType:CIDetectorTypeText
                                              context:nil options:nil];
    NSArray* features = [detector featuresInImage:cImage options:@{CIDetectorReturnSubFeatures:@YES}];
    CGSize inputImageSize = [cImage extent].size;
    CGAffineTransform  transform = CGAffineTransformIdentity;
    transform = CGAffineTransformScale(transform, 1, -1);
    transform = CGAffineTransformTranslate(transform, 0, -inputImageSize.height);

    for (CITextFeature *feature in features){
        NSLog(@"%@",feature.subFeatures);
        NSMutableDictionary * dic = [NSMutableDictionary dictionary];
        CGRect viewBounds = CGRectApplyAffineTransform(feature.bounds, transform);
        [dic setValue:[NSValue valueWithCGRect:viewBounds] forKey:@"rectBounds"];
        CGPoint topLeft = CGPointApplyAffineTransform(feature.topLeft, transform);
        [dic setValue:[NSValue valueWithCGPoint:topLeft] forKey:@"topLeft"];
        CGPoint topRight = CGPointApplyAffineTransform(feature.topRight, transform);
        [dic setValue:[NSValue valueWithCGPoint:topRight] forKey:@"topRight"];
        CGPoint bottomLeft = CGPointApplyAffineTransform(feature.bottomLeft, transform);
        [dic setValue:[NSValue valueWithCGPoint:bottomLeft] forKey:@"bottomLeft"];
        CGPoint bottomRight = CGPointApplyAffineTransform(feature.bottomRight, transform);
        [dic setValue:[NSValue valueWithCGPoint:bottomRight] forKey:@"bottomRight"];

        [dataArray addObject:dic];
    }
    return [dataArray copy];
}

效果如下图所示：

 

image

四、CoreImage中的相关核心类

1.CIColor类

CIColor类是CoreImage中描述色彩的类。

//通过CGColor创建CIColor
+ (instancetype)colorWithCGColor:(CGColorRef)c;
//构造方法
+ (instancetype)colorWithRed:(CGFloat)r green:(CGFloat)g blue:(CGFloat)b alpha:(CGFloat)a;
+ (instancetype)colorWithRed:(CGFloat)r green:(CGFloat)g blue:(CGFloat)b;
+ (nullable instancetype)colorWithRed:(CGFloat)r green:(CGFloat)g blue:(CGFloat)b alpha:(CGFloat)a colorSpace:(CGColorSpaceRef)colorSpace;
+ (nullable instancetype)colorWithRed:(CGFloat)r green:(CGFloat)g blue:(CGFloat)b colorSpace:(CGColorSpaceRef)colorSpace;
- (instancetype)initWithCGColor:(CGColorRef)c;
//通过字符串创建CIColor对象
+ (instancetype)colorWithString:(NSString *)representation;
- (instancetype)initWithRed:(CGFloat)r green:(CGFloat)g blue:(CGFloat)b alpha:(CGFloat)a;
- (instancetype)initWithRed:(CGFloat)r green:(CGFloat)g blue:(CGFloat)b;
- (nullable instancetype)initWithRed:(CGFloat)r green:(CGFloat)g blue:(CGFloat)b alpha:(CGFloat)a colorSpace:(CGColorSpaceRef)colorSpace;
- (nullable instancetype)initWithRed:(CGFloat)r green:(CGFloat)g blue:(CGFloat)b colorSpace:(CGColorSpaceRef)colorSpace;
//获取颜色分量个数
@property (readonly) size_t numberOfComponents;
//颜色分量
@property (readonly) const CGFloat *components;
//颜色透明度
@property (readonly) CGFloat alpha;
//色彩空间
@property (readonly) CGColorSpaceRef colorSpace;
//红绿蓝分量
@property (readonly) CGFloat red;
@property (readonly) CGFloat green;
@property (readonly) CGFloat blue;
//下面是定义的一些便捷的颜色变量
@property (class, strong, readonly) CIColor *blackColor  ;
@property (class, strong, readonly) CIColor *whiteColor  ;
@property (class, strong, readonly) CIColor *grayColor   ;
@property (class, strong, readonly) CIColor *redColor    ;
@property (class, strong, readonly) CIColor *greenColor  ;
@property (class, strong, readonly) CIColor *blueColor   ;
@property (class, strong, readonly) CIColor *cyanColor   ;
@property (class, strong, readonly) CIColor *magentaColor ;
@property (class, strong, readonly) CIColor *yellowColor  ;
@property (class, strong, readonly) CIColor *clearColor

2.CIImage类

CIImage是CoreImage中最核心的类，它描述了图像对象。

//创建一个新的CIImage实例
+ (CIImage *)imageWithCGImage:(CGImageRef)image;
//通过字典创建一个新的CIImage实例
/*
字典中的键
kCIImageColorSpace  设置颜色空间 为CGColorSpaceRef对象
kCIImageNearestSampling 是否临近采样  布尔值
kCIImageProperties    设置图片属性字典
kCIImageApplyOrientationProperty 布尔值 是否根据方向进行转换
kCIImageTextureTarget  NSNumber值 设置OpebGL目标纹理常数
kCIImageTextureFormat NSNumber值 设置OpebGL format
kCIImageAuxiliaryDepth 布尔值 是否返回深度图像
kCIImageAuxiliaryDisparity  布尔值 是否返回辅助时差图像
kCIImageAuxiliaryPortraitEffectsMatte  布尔值 是否返回肖像模板
*/
+ (CIImage *)imageWithCGImage:(CGImageRef)image
                      options:(nullable NSDictionary<CIImageOption, id> *)options;
//通过CALayer进行CIImage的创建
+ (CIImage *)imageWithCGLayer:(CGLayerRef)layer NS_DEPRECATED_MAC(10_4,10_11);
+ (CIImage *)imageWithCGLayer:(CGLayerRef)layer
                      options:(nullable NSDictionary<CIImageOption, id> *)options;
//使用bitmap数据创建CIImage
+ (CIImage *)imageWithBitmapData:(NSData *)data
                     bytesPerRow:(size_t)bytesPerRow
                            size:(CGSize)size
                          format:(CIFormat)format
                      colorSpace:(nullable CGColorSpaceRef)colorSpace;
//通过纹理创建CIImage
+ (CIImage *)imageWithTexture:(unsigned int)name
                         size:(CGSize)size
                      flipped:(BOOL)flipped
                   colorSpace:(nullable CGColorSpaceRef)colorSpace;
+ (CIImage *)imageWithTexture:(unsigned int)name
                         size:(CGSize)size
                      flipped:(BOOL)flipped
                      options:(nullable NSDictionary<CIImageOption, id> *)options;
+ (nullable CIImage *)imageWithMTLTexture:(id<MTLTexture>)texture
                                  options:(nullable NSDictionary<CIImageOption, id> *)options;
//通过url创建CIImage
+ (nullable CIImage *)imageWithContentsOfURL:(NSURL *)url;
+ (nullable CIImage *)imageWithContentsOfURL:(NSURL *)url
                                     options:(nullable NSDictionary<CIImageOption, id> *)options;
//通过NSDate创建CIImage
+ (nullable CIImage *)imageWithData:(NSData *)data;
+ (nullable CIImage *)imageWithData:(NSData *)data
                            options:(nullable NSDictionary<CIImageOption, id> *)options;
//通过CVImageBufferRef创建CIImage
+ (CIImage *)imageWithCVImageBuffer:(CVImageBufferRef)imageBuffer;
+ (CIImage *)imageWithCVImageBuffer:(CVImageBufferRef)imageBuffer
                            options:(nullable NSDictionary<CIImageOption, id> *)options;
//通过CVPixelBufferRef创建CIImage
+ (CIImage *)imageWithCVPixelBuffer:(CVPixelBufferRef)pixelBuffer;
+ (CIImage *)imageWithCVPixelBuffer:(CVPixelBufferRef)pixelBuffer
                            options:(nullable NSDictionary<CIImageOption, id> *)options;
//通过颜色创建CIImage
+ (CIImage *)imageWithColor:(CIColor *)color;
//创建空CIImage
+ (CIImage *)emptyImage;
//初始化方法
- (instancetype)initWithCGImage:(CGImageRef)image;
- (instancetype)initWithCGImage:(CGImageRef)image
                        options:(nullable NSDictionary<CIImageOption, id> *)options;
- (instancetype)initWithCGLayer:(CGLayerRef)layer);
- (instancetype)initWithCGLayer:(CGLayerRef)layer;
- (instancetype)initWithBitmapData:(NSData *)data
                       bytesPerRow:(size_t)bytesPerRow
                              size:(CGSize)size
                            format:(CIFormat)format
                        colorSpace:(nullable CGColorSpaceRef)colorSpace;
- (instancetype)initWithTexture:(unsigned int)name
                           size:(CGSize)size
                        flipped:(BOOL)flipped
                     colorSpace:(nullable CGColorSpaceRef)colorSpace;
- (instancetype)initWithTexture:(unsigned int)name
                           size:(CGSize)size
                        flipped:(BOOL)flipped
                        options:(nullable NSDictionary<CIImageOption, id> *)options;
- (nullable instancetype)initWithMTLTexture:(id<MTLTexture>)texture
                                    options:(nullable NSDictionary<CIImageOption, id> *)options；
- (nullable instancetype)initWithContentsOfURL:(NSURL *)url;
- (nullable instancetype)initWithContentsOfURL:(NSURL *)url
                                       options:(nullable NSDictionary<CIImageOption, id> *)options;
- (instancetype)initWithCVImageBuffer:(CVImageBufferRef)imageBuffer;
- (instancetype)initWithCVImageBuffer:(CVImageBufferRef)imageBuffer
                              options:(nullable NSDictionary<CIImageOption, id> *)options;
- (instancetype)initWithCVPixelBuffer:(CVPixelBufferRef)pixelBuffer;
- (instancetype)initWithCVPixelBuffer:(CVPixelBufferRef)pixelBuffer
                              options:(nullable NSDictionary<CIImageOption, id> *)options;
- (instancetype)initWithColor:(CIColor *)color;
//追加变换 返回结果CIImage对象
- (CIImage *)imageByApplyingTransform:(CGAffineTransform)matrix;
- (CIImage *)imageByApplyingOrientation:(int)orientation;
- (CIImage *)imageByApplyingCGOrientation:(CGImagePropertyOrientation)orientation;
//根据方向获取变换
- (CGAffineTransform)imageTransformForOrientation:(int)orientation;
- (CGAffineTransform)imageTransformForCGOrientation:(CGImagePropertyOrientation)orientation;
//进行混合
- (CIImage *)imageByCompositingOverImage:(CIImage *)dest;
//区域裁剪
- (CIImage *)imageByCroppingToRect:(CGRect)rect;
//返回图像边缘
- (CIImage *)imageByClampingToExtent;
//设置边缘 返回新图像对象
- (CIImage *)imageByClampingToRect:(CGRect)rect;
//用过滤器进行过滤
- (CIImage *)imageByApplyingFilter:(NSString *)filterName
               withInputParameters:(nullable NSDictionary<NSString *,id> *)params;
- (CIImage *)imageByApplyingFilter:(NSString *)filterName;
//图像边缘
@property (NS_NONATOMIC_IOSONLY, readonly) CGRect extent;
//属性字典
@property (atomic, readonly) NSDictionary<NSString *,id> *properties;
//通过URL创建的图像的URL
@property (atomic, readonly, nullable) NSURL *url;
//颜色空间
@property (atomic, readonly, nullable) CGColorSpaceRef colorSpace;
//通过CGImage创建的CGImage对象
@property (nonatomic, readonly, nullable) CGImageRef CGImage;

3.CIContext类

CIContext是CoreImage中的上下文对象，用来进行图片的渲染，已经转换为其他框架的图像对象。

//通过CGContextRef上下文创建CIContext上下文
/*
配置字典中可以进行配置的：
kCIContextOutputColorSpace   设置输出的颜色空间
kCIContextWorkingColorSpace  设置工作的颜色空间
kCIContextWorkingFormat      设置缓冲区数据格式
kCIContextHighQualityDownsample 布尔值
kCIContextOutputPremultiplied  设置输出是否带alpha通道
kCIContextCacheIntermediates  布尔值
kCIContextUseSoftwareRenderer 设置是否使用软件渲染
kCIContextPriorityRequestLow  是否低质量

*/
+ (CIContext *)contextWithCGContext:(CGContextRef)cgctx
                            options:(nullable NSDictionary<CIContextOption, id> *)options;
//创建上下文对象
+ (CIContext *)contextWithOptions:(nullable NSDictionary<CIContextOption, id> *)options;
+ (CIContext *)context;
- (instancetype)initWithOptions:(nullable NSDictionary<CIContextOption, id> *)options;
//使用指定的处理器创建CIContext
+ (CIContext *)contextWithMTLDevice:(id<MTLDevice>)device;
+ (CIContext *)contextWithMTLDevice:(id<MTLDevice>)device
                            options:(nullable NSDictionary<CIContextOption, id> *)options;
//工作的颜色空间
@property (nullable, nonatomic, readonly) CGColorSpaceRef workingColorSpace;
//缓冲区格式
@property (nonatomic, readonly) CIFormat workingFormat;
//进行CIImage图像的绘制
- (void)drawImage:(CIImage *)image
          atPoint:(CGPoint)atPoint
         fromRect:(CGRect)fromRect;
- (void)drawImage:(CIImage *)image
           inRect:(CGRect)inRect
         fromRect:(CGRect)fromRect;
//使用CIImage创建CGImageRef
- (nullable CGImageRef)createCGImage:(CIImage *)image;
                            fromRect:(CGRect)fromRect;
- (nullable CGImageRef)createCGImage:(CIImage *)image
                            fromRect:(CGRect)fromRect
                              format:(CIFormat)format
                          colorSpace:(nullable CGColorSpaceRef)colorSpace;
//创建CALayer
- (nullable CGLayerRef)createCGLayerWithSize:(CGSize)size
                                        info:(nullable CFDictionaryRef)info;
//将图片写入bitMap数据
- (void)render:(CIImage *)image
      toBitmap:(void *)data
      rowBytes:(ptrdiff_t)rowBytes
        bounds:(CGRect)bounds
        format:(CIFormat)format;
//将图片写入缓存
- (void)render:(CIImage *)image
toCVPixelBuffer:(CVPixelBufferRef)buffer
    colorSpace:(nullable CGColorSpaceRef)colorSpace;
- (void)render:(CIImage *)image
toCVPixelBuffer:(CVPixelBufferRef)buffer
        bounds:(CGRect)bounds
    colorSpace:(nullable CGColorSpaceRef)colorSpace；
//将图片写入纹理
- (void)render:(CIImage *)image
  toMTLTexture:(id<MTLTexture>)texture
 commandBuffer:(nullable id<MTLCommandBuffer>)commandBuffer
        bounds:(CGRect)bounds
    colorSpace:(CGColorSpaceRef)colorSpace;
//清除缓存
- (void)clearCaches;
//输入图像的最大尺寸
- (CGSize)inputImageMaximumSize;
//输出图像的最大尺寸
- (CGSize)outputImageMaximumSize;
//将CIImage写成TIFF数据
- (nullable NSData*) TIFFRepresentationOfImage:(CIImage*)image
                                        format:(CIFormat)format
                                    colorSpace:(CGColorSpaceRef)colorSpace
                                       options:(NSDictionary<CIImageRepresentationOption, id>*)options;
//将CIImage写成JPEG数据
- (nullable NSData*) JPEGRepresentationOfImage:(CIImage*)image
                                    colorSpace:(CGColorSpaceRef)colorSpace
                                       options:(NSDictionary<CIImageRepresentationOption, id>*)options;
//将CIImage写成HEIF数据
- (nullable NSData*) HEIFRepresentationOfImage:(CIImage*)image
                                        format:(CIFormat)format
                                    colorSpace:(CGColorSpaceRef)colorSpace
                                       options:(NSDictionary<CIImageRepresentationOption, id>*)options;
//将CIImage写成PNG数据
- (nullable NSData*) PNGRepresentationOfImage:(CIImage*)image
                                       format:(CIFormat)format
                                   colorSpace:(CGColorSpaceRef)colorSpace
                                      options:(NSDictionary<CIImageRepresentationOption, id>*)options;
//将CIImage写入TIFF文件
- (BOOL) writeTIFFRepresentationOfImage:(CIImage*)image
                                  toURL:(NSURL*)url
                                 format:(CIFormat)format
                             colorSpace:(CGColorSpaceRef)colorSpace
                                options:(NSDictionary<CIImageRepresentationOption, id>*)options
                                  error:(NSError **)errorPtr;
//将CIImage写入PNG文件
- (BOOL) writePNGRepresentationOfImage:(CIImage*)image
                                 toURL:(NSURL*)url
                                format:(CIFormat)format
                            colorSpace:(CGColorSpaceRef)colorSpace
                               options:(NSDictionary<CIImageRepresentationOption, id>*)options
                                 error:(NSError **)errorPtr;
//将CIImage写入JPEG文件
- (BOOL) writeJPEGRepresentationOfImage:(CIImage*)image
                                  toURL:(NSURL*)url
                             colorSpace:(CGColorSpaceRef)colorSpace
                                options:(NSDictionary<CIImageRepresentationOption, id>*)options
                                  error:(NSError **)errorPtr;
//将CIImage写HEIF文件
- (BOOL) writeHEIFRepresentationOfImage:(CIImage*)image
                                  toURL:(NSURL*)url
                                 format:(CIFormat)format
                             colorSpace:(CGColorSpaceRef)colorSpace
                                options:(NSDictionary<CIImageRepresentationOption, id>*)options
                                  error:(NSError **)errorPtr;

4.CIDetector类

前面有过CIDetector类的功能演示，这是CIImage框架中非常强大的一个类，使用它可以进行复杂的图片识别技术，解析如下：

//创建CIDetector实例
/*
type用来指定识别的类型
CIDetectorTypeFace  人脸识别模式
CIDetectorTypeRectangle 矩形检测模式
CIDetectorTypeText   文本区域检测模式
CIDetectorTypeQRCode 二维码扫描模式

option可以指定配置字典 可配置的键如下
CIDetectorAccuracy 设置检测精度 CIDetectorAccuracyLow 低 CIDetectorAccuracyHigh 高
CIDetectorTracking 设置是否跟踪特征
CIDetectorMinFeatureSize  设置特征最小尺寸 0-1之间 相对图片
CIDetectorMaxFeatureCount 设置最大特征数
CIDetectorImageOrientation 设置方向
CIDetectorEyeBlink  设置布尔值 是否提取面部表情 眨眼
CIDetectorSmile    设置布尔值 是否提取面部表情  微笑
CIDetectorFocalLength  设置焦距
CIDetectorAspectRatio 设置检测到矩形的宽高比
CIDetectorReturnSubFeatures 设置是否提取子特征

*/
+ (nullable CIDetector *)detectorOfType:(NSString*)type
                                context:(nullable CIContext *)context
                                options:(nullable NSDictionary<NSString *,id> *)options;
//进行图片分析 提取特征数组
- (NSArray<CIFeature *> *)featuresInImage:(CIImage *)image;
- (NSArray<CIFeature *> *)featuresInImage:(CIImage *)image
                                  options:(nullable NSDictionary<NSString *,id> *)options;

5.CIFeature相关类

CIFeature与其相关子类定义了特征数据模型。

@interface CIFeature : NSObject {}
//特征类型
/*
CIFeatureTypeFace
CIFeatureTypeRectangle
CIFeatureTypeQRCode
CIFeatureTypeText
*/
@property (readonly, retain) NSString *type;
//特征在图片中的bounds
@property (readonly, assign) CGRect bounds;
@end

//人脸特征对象
@interface CIFaceFeature : CIFeature
//位置尺寸
@property (readonly, assign) CGRect bounds;
//左眼位置
@property (readonly, assign) BOOL hasLeftEyePosition;
@property (readonly, assign) CGPoint leftEyePosition;
//是否有左眼特征
@property (readonly, assign) BOOL hasRightEyePosition;
//右眼位置
@property (readonly, assign) CGPoint rightEyePosition;
//是否有右眼特征
@property (readonly, assign) BOOL hasMouthPosition;
//口部特征
@property (readonly, assign) CGPoint mouthPosition;
//是否有跟踪特征ID
@property (readonly, assign) BOOL hasTrackingID;
//跟踪特征ID
@property (readonly, assign) int trackingID;
@property (readonly, assign) BOOL hasTrackingFrameCount;
@property (readonly, assign) int trackingFrameCount;
@property (readonly, assign) BOOL hasFaceAngle;
@property (readonly, assign) float faceAngle;
//是否微笑
@property (readonly, assign) BOOL hasSmile;
//左眼是否闭眼
@property (readonly, assign) BOOL leftEyeClosed;
//右眼是否闭眼
@property (readonly, assign) BOOL rightEyeClosed;

@end

//矩形特征对象
@interface CIRectangleFeature : CIFeature
//位置尺寸
@property (readonly) CGRect bounds;
@property (readonly) CGPoint topLeft;
@property (readonly) CGPoint topRight;
@property (readonly) CGPoint bottomLeft;
@property (readonly) CGPoint bottomRight;

@end

//二维码特征对象
@interface CIQRCodeFeature : CIFeature
//位置尺寸信息
@property (readonly) CGRect bounds;
@property (readonly) CGPoint topLeft;
@property (readonly) CGPoint topRight;
@property (readonly) CGPoint bottomLeft;
@property (readonly) CGPoint bottomRight;
//二维码内容
@property (nullable, readonly) NSString* messageString;
//二维码描述数据
@property (nullable, readonly) CIQRCodeDescriptor *symbolDescriptor NS_AVAILABLE(10_13, 11_0);

@end

//文本特征对象
@interface CITextFeature : CIFeature
//位置信息
@property (readonly) CGRect bounds;
@property (readonly) CGPoint topLeft;
@property (readonly) CGPoint topRight;
@property (readonly) CGPoint bottomLeft;
@property (readonly) CGPoint bottomRight;
//子特征
@property (nullable, readonly) NSArray *subFeatures;

@end

 

iOS开发之CoreImage框架使用(上)

iOS开发之CoreImage框架使用(下)