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:

- 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:

- 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:

- 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:

- 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:

- 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:

- 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:

- 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:

- 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:

- 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:

- 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:

- 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:

- 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:

- 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:

- 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:

- 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:

- 旋转矫正过滤器
CIFilter * filter = [CIFilter filterWithName:@"CIStraightenFilter" keysAndValues:kCIInputImageKey,image2,@"inputAngle",@3.14,nil];
效果如下:

- 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:

- 色彩混合过滤器
CIFilter * filter = [CIFilter filterWithName:@"CIColorBlendMode" keysAndValues:kCIInputImageKey,image2,@"inputBackgroundImage",image,nil];
效果如下:

- 暗混合过滤器
CIFilter * filter = [CIFilter filterWithName:@"CIColorBurnBlendMode" keysAndValues:kCIInputImageKey,image2,@"inputBackgroundImage",image,nil];
效果如下:

- 亮混合过滤器
CIFilter * filter = [CIFilter filterWithName:@"CIColorDodgeBlendMode" keysAndValues:kCIInputImageKey,image2,@"inputBackgroundImage",image,nil];

- 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:

- 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:

- 分开混合模式过滤器
CIFilter * filter = [CIFilter filterWithName:@"CIDivideBlendMode" keysAndValues:kCIInputImageKey,image2,@"inputBackgroundImage",image,nil];
效果如下:

- 排除混合模式过滤器
CIFilter * filter = [CIFilter filterWithName:@"CIExclusionBlendMode" keysAndValues:kCIInputImageKey,image2,@"inputBackgroundImage",image,nil];
效果如下:

- 强光混合模式过滤器
CIFilter * filter = [CIFilter filterWithName:@"CIHardLightBlendMode" keysAndValues:kCIInputImageKey,image2,@"inputBackgroundImage",image,nil];
效果如下:

- 色调混合模式过滤器
CIFilter * filter = [CIFilter filterWithName:@"CIHueBlendMode" keysAndValues:kCIInputImageKey,image2,@"inputBackgroundImage",image,nil];
效果如下:

- 减轻混合模式过滤器
CIFilter * filter = [CIFilter filterWithName:@"CILightenBlendMode" keysAndValues:kCIInputImageKey,image2,@"inputBackgroundImage",image,nil];
效果如下:

- 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:

- 线性高亮混合过滤器
CIFilter * filter = [CIFilter filterWithName:@"CILinearDodgeBlendMode" keysAndValues:kCIInputImageKey,image2,@"inputBackgroundImage",image,nil];
效果如下:

- 亮度混合过滤器
CIFilter * filter = [CIFilter filterWithName:@"CILuminosityBlendMode" keysAndValues:kCIInputImageKey,image2,@"inputBackgroundImage",image,nil];
效果如下:

- 最大值混合过滤器
CIFilter * filter = [CIFilter filterWithName:@"CIMaximumCompositing" keysAndValues:kCIInputImageKey,image2,@"inputBackgroundImage",image,nil];
效果如下:

- 最小值混合过滤器
CIFilter * filter = [CIFilter filterWithName:@"CIMinimumCompositing" keysAndValues:kCIInputImageKey,image2,@"inputBackgroundImage",image,nil];
效果如下:

- 多重混合过滤器
CIFilter * filter = [CIFilter filterWithName:@"CIMultiplyBlendMode" keysAndValues:kCIInputImageKey,image2,@"inputBackgroundImage",image,nil];
效果如下:

- 多重合成过滤器
CIFilter * filter = [CIFilter filterWithName:@"CIMultiplyCompositing" keysAndValues:kCIInputImageKey,image2,@"inputBackgroundImage",image,nil];

- 重叠混合模式
CIFilter * filter = [CIFilter filterWithName:@"CIOverlayBlendMode" keysAndValues:kCIInputImageKey,image2,@"inputBackgroundImage",image,nil];

- 亮混合模式
CIFilter * filter = [CIFilter filterWithName:@"CIPinLightBlendMode" keysAndValues:kCIInputImageKey,image2,@"inputBackgroundImage",image,nil];

- 饱和混合模式
CIFilter * filter = [CIFilter filterWithName:@"CISaturationBlendMode" keysAndValues:kCIInputImageKey,image2,@"inputBackgroundImage",image,nil];

- 屏幕混合模式
CIFilter * filter = [CIFilter filterWithName:@"CIScreenBlendMode" keysAndValues:kCIInputImageKey,image2,@"inputBackgroundImage",image,nil];

- 源图像上层混合
CIFilter * filter = [CIFilter filterWithName:@"CISourceAtopCompositing" keysAndValues:kCIInputImageKey,image2,@"inputBackgroundImage",image,nil];

- 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];

- 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];

- 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];

- 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];

- 线性sRGB过滤器
CIFilter * filter = [CIFilter filterWithName:@"CILinearToSRGBToneCurve" keysAndValues:kCIInputImageKey,image2,nil];

- 色彩翻转过滤器
CIFilter * filter = [CIFilter filterWithName:@"CIColorInvert" keysAndValues:kCIInputImageKey,image2,nil];

- 色图过滤器
CIFilter * filter = [CIFilter filterWithName:@"CIColorMap" keysAndValues:kCIInputImageKey,image2,@"inputGradientImage",image,nil];

- 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];

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

- 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];

- 光效褪色过滤器
CIFilter * filter = [CIFilter filterWithName:@"CIPhotoEffectFade" keysAndValues:kCIInputImageKey,image2,nil];

- 光效瞬时过滤器
CIFilter * filter = [CIFilter filterWithName:@"CIPhotoEffectInstant" keysAndValues:kCIInputImageKey,image2,nil];

- 光效单光过滤器
CIFilter * filter = [CIFilter filterWithName:@"CIPhotoEffectMono" keysAndValues:kCIInputImageKey,image2,nil];

- 黑色光效应过滤器
CIFilter * filter = [CIFilter filterWithName:@"CIPhotoEffectNoir" keysAndValues:kCIInputImageKey,image2,nil];

- 光渐进过滤器
CIFilter * filter = [CIFilter filterWithName:@"CIPhotoEffectProcess" keysAndValues:kCIInputImageKey,image2,nil];

- 光转移过滤器
CIFilter * filter = [CIFilter filterWithName:@"CIPhotoEffectTransfer" keysAndValues:kCIInputImageKey,image2,nil];

- 棕褐色过滤器
CIFilter * filter = [CIFilter filterWithName:@"CISepiaTone" keysAndValues:kCIInputImageKey,image2,nil];

- 热图过滤器
CIFilter * filter = [CIFilter filterWithName:@"CIThermal" keysAndValues:kCIInputImageKey,image2,nil];

- X射线过滤器
CIFilter * filter = [CIFilter filterWithName:@"CIXRay" keysAndValues:kCIInputImageKey,image2,nil];

- 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];

- 盒模糊过滤器
CIFilter * filter = [CIFilter filterWithName:@"CIBoxBlur" keysAndValues:kCIInputImageKey,image2,@"inputRadius",@10,nil];

- 阀瓣模糊过滤器
CIFilter * filter = [CIFilter filterWithName:@"CIDiscBlur" keysAndValues:kCIInputImageKey,image2,@"inputRadius",@25,nil];

- 高斯模糊过滤器
CIFilter * filter = [CIFilter filterWithName:@"CIGaussianBlur" keysAndValues:kCIInputImageKey,image2,@"inputRadius",@10,nil];

- 梯度模糊过滤器
CIFilter * filter = [CIFilter filterWithName:@"CIMorphologyGradient" keysAndValues:kCIInputImageKey,image2,@"inputRadius",@5,nil];

- 运动模糊过滤器
CIFilter * filter = [CIFilter filterWithName:@"CIMotionBlur" keysAndValues:kCIInputImageKey,image2,@"inputRadius",@5,nil];

- 缩放模糊过滤器
CIFilter * filter = [CIFilter filterWithName:@"CIZoomBlur" keysAndValues:kCIInputImageKey,image2,nil];

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];
网友评论