第一部分: 安装
一. 安装: Adding the framework to your iOS project 

1. 把GPUImage.xcodeproj 拖到你的Xcode project


2. 在app的target依赖设置里面添加GPUImage作为Target Dependency


3. 在build phase的Link Binary With Libraries, 把libGPUImage.a加进来.


4. 添加下面这些系统framework:


•  CoreMedia
•  CoreVideo
•  OpenGLES
•  AVFoundation
•  QuartzCore

5. 头文件搜索路径: project's build settings, 把GPUImage的source和source下的iOS目录加到搜索路径里, 使用相对路径和递归.


6. 包含下面这个头文件:





1.  #import "GPUImage.h"


      复制代码



二. 静态库方法



 Building static library at the command line 

If you don't want to include the project as a dependency in your application's Xcode project, you can build a universal static library for the iOS Simulator or device. To do this, run build.sh at the command line. The resulting library and header files will be located at build/Release-iphone. You may also change the version of the iOS SDK by changing the IOSSDK_VER variable in build.sh (all available versions can be found using xcodebuild -showsdks).

第二部分: 使用


一. Filtering live video




1.  GPUImageVideoCamera *videoCamera = [[GPUImageVideoCamera alloc] initWithSessionPreset:AVCaptureSessionPreset640x480 cameraPosition:AVCaptureDevicePositionBack];
2.  videoCamera.outputImageOrientation = UIInterfaceOrientationPortrait;
3. 4.  GPUImageFilter *customFilter = [[GPUImageFilter alloc] initWithFragmentShaderFromFile:@"CustomShader"];
5.  GPUImageView *filteredVideoView = [[GPUImageView alloc] initWithFrame:CGRectMake(0.0, 0.0, viewWidth, viewHeight)];
6. 7.  // Add the view somewhere so it's visible
8. 9.  [videoCamera addTarget:customFilter];
10.  [customFilter addTarget:filteredVideoView];
11. 12.  [videoCamera startCameraCapture];


     复制代码



1. 首先建立一个outputs, 对video情况是video source:  videoCamera,  采用背部主相机, 已经预设的(preset) 640x480, 并采用portrait模式, 如果是landscape left下拍摄的,需要自己旋转一下来显示.


2. 建立一个filter, customFilter, 并设置为video source的target.


3. 建立一个显示view, 并设置为filter的target.  可以设置显示view的fillMode


4. 开始action:   [videoCamera startCameraCapture];





从 outputs -> filter -> display view 是一个 filter chain,  如果有多个outputs进行混合(blend), 把他们的target都设成相同的filter就可以了.


如果要是记录电影的话:可以使用下面这句进行声音捕捉.








1.  videoCamera.audioEncodingTarget = movieWriter;


      复制代码



二. Capturing and filtering a still photo


相机预览代码:  (此时虽然是相机模式, 仍然会给出一个still camera的预览视频)




1.  stillCamera = [[GPUImageStillCamera alloc] init];
2.  stillCamera.outputImageOrientation = UIInterfaceOrientationPortrait;
3. 4.  filter = [[GPUImageGammaFilter alloc] init];
5.  [stillCamera addTarget:filter];
6.  GPUImageView *filterView = (GPUImageView *)self.view;
7.  [filter addTarget:filterView];
8. 9.  [stillCamera startCameraCapture];


     复制代码



拍照代码:




1.  [stillCamera capturePhotoProcessedUpToFilter:filter withCompletionHandler:^(UIImage *processedImage, NSError *error){
2.      NSData *dataForPNGFile = UIImageJPEGRepresentation(processedImage, 0.8);
3. 4.      NSArray *paths = NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES);
5.      NSString *documentsDirectory = [paths objectAtIndex:0];
6. 7.      NSError *error2 = nil;
8.      if (![dataForPNGFile writeToFile:[documentsDirectory stringByAppendingPathComponent:@"FilteredPhoto.jpg"] options:NSAtomicWrite error:&error2])
9.      {
10.          return;
11.      }
12.  }];


     复制代码



三. Processing a still image




1.  UIImage *inputImage = [UIImage imageNamed:@"Lambeau.jpg"];
2. 3.  GPUImagePicture *stillImageSource = [[GPUImagePicture alloc] initWithImage:inputImage];
4.  GPUImageSepiaFilter *stillImageFilter = [[GPUImageSepiaFilter alloc] init];
5. 6.  [stillImageSource addTarget:stillImageFilter];
7.  [stillImageSource processImage];
8. 9.  UIImage *currentFilteredVideoFrame = [stillImageFilter imageFromCurrentlyProcessedOutput];


     复制代码



一个filter下更简单的方法:




1.  GPUImageSepiaFilter *stillImageFilter2 = [[GPUImageSepiaFilter alloc] init];
2.  UIImage *quickFilteredImage = [stillImageFilter2 imageByFilteringImage:inputImage];
3. 


     复制代码



四. 自定义滤镜

从bundle里面加载OpenGL Shading Language编写的 fragment shader文件, 后缀是 .fsh  或者从字符串里面加载.




1.  GPUImageFilter *customFilter = [[GPUImageFilter alloc] initWithFragmentShaderFromFile:@"CustomShader"];


     复制代码





1.  NSString *const kfilterShader = SHADER_STRING
2.  (
3.  ...
4.  );


     复制代码



一个脚本的例子:




1.  varying highp vec2 textureCoordinate;
2. 3.  uniform sampler2D inputImageTexture;
4. 5.  void main()
6.  {
7.      lowp vec4 textureColor = texture2D(inputImageTexture, textureCoordinate);
8.      lowp vec4 outputColor;
9.      outputColor.r = (textureColor.r * 0.393) + (textureColor.g * 0.769) + (textureColor.b * 0.189);
10.      outputColor.g = (textureColor.r * 0.349) + (textureColor.g * 0.686) + (textureColor.b * 0.168);    
11.      outputColor.b = (textureColor.r * 0.272) + (textureColor.g * 0.534) + (textureColor.b * 0.131);
12.      outputColor.a = 1.0;
13. 14.      gl_FragColor = outputColor;
15.  }


     复制代码



这段脚本有一个varing, 表示的是材质的2D坐标, 一个unifrom是材质的图片.


main函数里面把这个坐标的颜色取出来处理后生成新的颜色, 交给gl_FragColor传递个pipeline的下一个单元. 在这里也就是最终输出.





五. Filtering and re-encoding a movie




1.  movieFile = [[GPUImageMovie alloc] initWithURL:sampleURL];
2.  pixellateFilter = [[GPUImagePixellateFilter alloc] init];
3. 4.  [movieFile addTarget:pixellateFilter];
5. 6.  NSString *pathToMovie = [NSHomeDirectory() stringByAppendingPathComponent:@"Documents/Movie.m4v"];
7.  unlink([pathToMovie UTF8String]);
8.  NSURL *movieURL = [NSURL fileURLWithPath:pathToMovie];
9. 10.  movieWriter = [[GPUImageMovieWriter alloc] initWithMovieURL:movieURL size:CGSizeMake(480.0, 640.0)];
11.  [pixellateFilter addTarget:movieWriter];
12. 13.  movieWriter.shouldPassthroughAudio = YES;
14.  movieFile.audioEncodingTarget = movieWriter;
15.  [movieFile enableSynchronizedEncodingUsingMovieWriter:movieWriter];
16. 17.  [movieWriter startRecording];
18.  [movieFile startProcessing];


     复制代码



GPUImageMovie作为源, 中间是filter, 最终是GPUImageMovieWriter来写入文件.  这段代码是输出480 x 640 h.264 movie


GPUImageMovieWriter非常快, 能够实时的保存iPhone 4的640x480到输出文件, 在iPhone4上, 720p能20fps的速度输出, iPhone 4S上720p 和 1080p都能达到30 FPS

结束的时候停止代码:




1.  [pixellateFilter removeTarget:movieWriter];
2.  [movieWriter finishRecording];


     复制代码



如果不停止, 输出文件不可用, 如果中间被打断, 输出文件会丢失.

六. Interacting with OpenGL ES

GPUImage使用GPUImageTextureOutput 和 GPUImageTextureInput 想Open GL ES 2.0输出或者输入材质, 可用把GPUImage的输出作为OpenGL的材质输入, 或者把OpenGL的输出作为自己的材质输入.


例子代码正在整理中


第三部分, 原理

 GPUImage是一个链(chain),     source -> phase1 target -> phase2 target -> final target

 第一个环节是source, 这是一些GPUImageOutput的子类.包括:
(1). GPUImageVideoCamera (for live video from an iOS camera)
(2.) GPUImageStillCamera (for taking photos with the camera)
(3). GPUImagePicture (for still images) 
(4). GPUImageMovie (for movies). S

 后续环节是被称为target.  遵循GPUImageInput protocol

可用多个source到一个target上面进行blend,  也可用进行分支, 添加多个target.

 一般的target可分为两类
 (1)中间环节的target,  一般是各种filter, 是GPUImageFilter或者是子类.
(2)最终环节的target, 可用是GPUImageView, 或者GPUImageMovieWriter


一个典型的例子




1.  GPUImageVideoCamera -> GPUImageSepiaFilter -> GPUImageView


     复制代码

 第四部分, 内置滤镜列表


 共125个滤镜, 分为四类
 Color adjustments:  31 filters, 颜色处理相关
 Image processing:   40 filters, 图像处理相关.
 Blending modes:     29 filters,  混合模式相关.
 Visual effects:     25 filters,  视觉效果相关.


 下面分别列出车125个滤镜的名字, 后续再对每个专题进行讲解.

 Color adjustments:  31 filters
     GPUImageBrightnessFilter
     GPUImageExposureFilter
     GPUImageContrastFilter
     GPUImageSaturationFilter
     GPUImageGammaFilter
     GPUImageLevelsFilter
     GPUImageColorMatrixFilter
     GPUImageRGBFilter
     GPUImageHueFilter
     GPUImageToneCurveFilter

     GPUImageHighlightShadowFilter

     GPUImageLookupFilter
     GPUImageAmatorkaFilter
     GPUImageMissEtikateFilter
     GPUImageSoftEleganceFilter

     GPUImageColorInvertFilter
     GPUImageGrayscaleFilter
     GPUImageMonochromeFilter
     GPUImageFalseColorFilter

     GPUImageHazeFilter

     GPUImageSepiaFilter
     GPUImageOpacityFilter
     GPUImageSolidColorGenerator

     GPUImageLuminanceThresholdFilter
     GPUImageAdaptiveThresholdFilter
     GPUImageAverageLuminanceThresholdFilter
     GPUImageHistogramFilter
     GPUImageHistogramGenerator
     GPUImageAverageColor
     GPUImageLuminosity

     GPUImageChromaKeyFilter 


 Image processing:  40 filters
     GPUImageTransformFilter
     GPUImageCropFilter
     GPUImageLanczosResamplingFilter
     GPUImageSharpenFilter
     GPUImageUnsharpMaskFilter
     GPUImageGaussianBlurFilter
     GPUImageBoxBlurFilter
     GPUImageSingleComponentGaussianBlurFilter
     GPUImageGaussianSelectiveBlurFilter
     GPUImageGaussianBlurPositionFilter
     GPUImageiOSBlurFilter
     GPUImageMedianFilter
     GPUImageBilateralFilter
     GPUImageTiltShiftFilter
     GPUImage3x3ConvolutionFilter
     GPUImageSobelEdgeDetectionFilter
     GPUImagePrewittEdgeDetectionFilter
     GPUImageThresholdEdgeDetectionFilter
     GPUImageCannyEdgeDetectionFilter
     GPUImageHarrisCornerDetectionFilter
     GPUImageNobleCornerDetectionFilter
     GPUImageShiTomasiCornerDetectionFilter
     GPUImageNonMaximumSuppressionFilter
     GPUImageXYDerivativeFilter
     GPUImageCrosshairGenerator
     GPUImageDilationFilter
     GPUImageRGBDilationFilter
     GPUImageErosionFilter
     GPUImageRGBErosionFilter
     GPUImageOpeningFilter
     GPUImageRGBOpeningFilter
     GPUImageClosingFilter
     GPUImageRGBClosingFilter
     GPUImageLocalBinaryPatternFilter
     GPUImageLowPassFilter
     GPUImageHighPassFilter
     GPUImageMotionDetector
     GPUImageHoughTransformLineDetector
     GPUImageLineGenerator
     GPUImageMotionBlurFilter

 Blending modes: 29 filters
     GPUImageZoomBlurFilter
     GPUImageChromaKeyBlendFilter
     GPUImageDissolveBlendFilter
     GPUImageMultiplyBlendFilter
     GPUImageAddBlendFilter
     GPUImageSubtractBlendFilter
     GPUImageDivideBlendFilter
     GPUImageOverlayBlendFilter
     GPUImageDarkenBlendFilter
     GPUImageLightenBlendFilter
     GPUImageColorBurnBlendFilter
     GPUImageColorDodgeBlendFilter
     GPUImageScreenBlendFilter
     GPUImageExclusionBlendFilter
     GPUImageDifferenceBlendFilter
     GPUImageHardLightBlendFilter
     GPUImageSoftLightBlendFilter
     GPUImageAlphaBlendFilter
     GPUImageSourceOverBlendFilter
     GPUImageColorBurnBlendFilter
     GPUImageColorDodgeBlendFilter
     GPUImageNormalBlendFilter
     GPUImageColorBlendFilter
     GPUImageHueBlendFilter
     GPUImageSaturationBlendFilter
     GPUImageLuminosityBlendFilter
     GPUImageLinearBurnBlendFilter
     GPUImagePoissonBlendFilter
     GPUImageMaskFilter

 Visual effects: 25 filters
     GPUImagePixellateFilter
     GPUImagePolarPixellateFilter
     GPUImagePolkaDotFilter
     GPUImageHalftoneFilter
     GPUImageCrosshatchFilter
     GPUImageSketchFilter
     GPUImageThresholdSketchFilter
     GPUImageToonFilter
     GPUImageSmoothToonFilter
     GPUImageEmbossFilter
     GPUImagePosterizeFilter
     GPUImageSwirlFilter
     GPUImageBulgeDistortionFilter
     GPUImagePinchDistortionFilter
     GPUImageStretchDistortionFilter
     GPUImageSphereRefractionFilter
     GPUImageGlassSphereFilter
     GPUImageVignetteFilter
     GPUImageKuwaharaFilter
     GPUImageKuwaharaRadius3Filter
     GPUImagePerlinNoiseFilter
     GPUImageCGAColorspaceFilter
     GPUImageMosaicFilter
     GPUImageJFAVoronoiFilter
     GPUImageVoronoiConsumerFilter