1、本文主要涉及到opencv的视频帧抓拍和验证的相关问题，不包含如何集成opencv

2、主要讲解涉及到opencv中的关键类及一些常用的方法

3、着重讲解代理方法：

- (void)processImage:(cv::Mat &)image

4、集成过程中的注意事项

5、附上抓拍的小demo的下载地址

6、扩展，验证抓拍的图片中是否包含人脸

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以下为正文

一、集成opencv需要添加的framework和静态库

二、OpenCV使用过程中的关键类及一些常用的方法

1、cap_ios.h、以下为此类的原始代码

/* For iOS video I/O

* by Eduard Feicho on 29/07/12

* Copyright 2012. All rights reserved.

*

* Redistribution and use in source and binary forms, with or without

* modification, are permitted provided that the following conditions are met:

*

* 1. Redistributions of source code must retain the above copyright notice,

* this list of conditions and the following disclaimer.

* 2. Redistributions in binary form must reproduce the above copyright notice,

* this list of conditions and the following disclaimer in the documentation

* and/or other materials provided with the distribution.

* 3. The name of the author may not be used to endorse or promote products

* derived from this software without specific prior written permission.

*

* THIS SOFTWARE IS PROVIDED BY THE AUTHOR "AS IS" AND ANY EXPRESS OR IMPLIED

* WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF

* MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO

* EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,

* SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,

* PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS;

* OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY,

* WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR

* OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF

* ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.

*

*/

#import

#import

#import

#import

#include "opencv2/core.hpp"

//! @addtogroup videoio_ios

//! @{

/// CvAbstractCamera /

@class CvAbstractCamera;

CV_EXPORTS @interface CvAbstractCamera : NSObject

{

UIDeviceOrientation currentDeviceOrientation;

BOOL cameraAvailable;

}

@property (nonatomic, strong) AVCaptureSession* captureSession;

@property (nonatomic, strong) AVCaptureConnection* videoCaptureConnection;

@property (nonatomic, readonly) BOOL running;

@property (nonatomic, readonly) BOOL captureSessionLoaded;

@property (nonatomic, assign) int defaultFPS;

@property (nonatomic, readonly) AVCaptureVideoPreviewLayer *captureVideoPreviewLayer;

@property (nonatomic, assign) AVCaptureDevicePosition defaultAVCaptureDevicePosition;

@property (nonatomic, assign) AVCaptureVideoOrientation defaultAVCaptureVideoOrientation;

@property (nonatomic, assign) BOOL useAVCaptureVideoPreviewLayer;

@property (nonatomic, strong) NSString *const defaultAVCaptureSessionPreset;

@property (nonatomic, assign) int imageWidth;

@property (nonatomic, assign) int imageHeight;

@property (nonatomic, strong) UIView* parentView;

- (void)start;

- (void)stop;

- (void)switchCameras;

- (id)initWithParentView:(UIView*)parent;

- (void)createCaptureOutput;

- (void)createVideoPreviewLayer;

- (void)updateOrientation;

- (void)lockFocus;

- (void)unlockFocus;

- (void)lockExposure;

- (void)unlockExposure;

- (void)lockBalance;

- (void)unlockBalance;

@end

/ CvVideoCamera ///

@class CvVideoCamera;

CV_EXPORTS @protocol CvVideoCameraDelegate

#ifdef __cplusplus

// delegate method for processing image frames

- (void)processImage:(cv::Mat&)image;

#endif

@end

CV_EXPORTS @interface CvVideoCamera : CvAbstractCamera

{

AVCaptureVideoDataOutput *videoDataOutput;

dispatch_queue_t videoDataOutputQueue;

CALayer *customPreviewLayer;

CMTime lastSampleTime;

}

@property (nonatomic, weak) id delegate;

@property (nonatomic, assign) BOOL grayscaleMode;

@property (nonatomic, assign) BOOL recordVideo;

@property (nonatomic, assign) BOOL rotateVideo;

@property (nonatomic, strong) AVAssetWriterInput* recordAssetWriterInput;

@property (nonatomic, strong) AVAssetWriterInputPixelBufferAdaptor* recordPixelBufferAdaptor;

@property (nonatomic, strong) AVAssetWriter* recordAssetWriter;

- (void)adjustLayoutToInterfaceOrientation:(UIInterfaceOrientation)interfaceOrientation;

- (void)layoutPreviewLayer;

- (void)saveVideo;

- (NSURL *)videoFileURL;

- (NSString *)videoFileString;

@end

/ CvPhotoCamera ///

@class CvPhotoCamera;

CV_EXPORTS @protocol CvPhotoCameraDelegate

- (void)photoCamera:(CvPhotoCamera*)photoCamera capturedImage:(UIImage *)image;

- (void)photoCameraCancel:(CvPhotoCamera*)photoCamera;

@end

CV_EXPORTS @interface CvPhotoCamera : CvAbstractCamera

{

AVCaptureStillImageOutput *stillImageOutput;

}

@property (nonatomic, weak) id delegate;

- (void)takePicture;

@end

//! @} videoio_ios

以上方法从名知意，且命名简洁明了，无需过多的注释说明 ，此为值得我等ITboy学习和观摩的地方

2、关键方法说明

此处不对CvPhotoCamera做说明，主要针对 CvVideoCameraDelegate 的代理方法进行说明

- (void)processImage:(cv::Mat&)image;

此方法视频帧的抓取代理，其中的image对象为非正常的RGB对象，为一个灰度对象，在使用过程中，需要进行色值的转换

- (void)processImage:(cv::Mat &)image

{

cv::Mat outCopyImg;

image.copyTo(outCopyImg);

cv::cvtColor(outCopyImg, outCopyImg, CV_BGR2RGB);

//此处说明：cv::cvtColor为颜色转换方法，最后一个参数即为我们常用的RGB色值if([self whetherTheImageBlurry:image]) {

//此为一个清晰度的验证，也是来自于网上的摘录，下方会贴出代码

[self.videoCamera stop];

keepMatImg=outCopyImg;if (isNeedToCut ==YES) {

CGFloat mianW=UIScreen.mainScreen.bounds.size.width;

CGFloat NH= mianW * 1920 / 1080;

cv::Rect rect(0,(1920 - NH)/2,1080,NH);

cv::Mat image_roi=outCopyImg(rect);

self.keepImageAlive=MatToUIImage(image_roi);

//说明：网上有很多将cv::Mat类型的数据转换为UIimage的方法 ，但是OpenCV本身就提供了此方法 MatToUIImage()，所以此处不再引用其他方法

}else{

self.keepImageAlive=MatToUIImage(outCopyImg);

}

NSLog(@"keepImageAlive.size = %@",NSStringFromCGSize(self.keepImageAlive.size));

dispatch_async(dispatch_get_main_queue(),^{if(self.keepImageAlive) {

self.fuzzyText.text= @"清晰";

self.resultImageView.image=self.keepImageAlive;

self.resultImageView.hidden=NO;

}

});

}else{

dispatch_sync(dispatch_get_main_queue(),^{

self.fuzzyText.text= @"模糊";

});

}

}

3、清晰度的验证的方法

- (BOOL)whetherTheImageBlurry:(cv::Mat)mat{

unsigned char *data;

int height,width,step;

int Iij;

double Iave = 0, Idelta = 0;

// cv::Mat mat = [OpenCVExtension cvMatFromUIImage:image];

if(!mat.empty()){

cv::Mat gray;

cv::Mat outGray;

// 将图像转换为灰度显示

cv::cvtColor(mat,gray,CV_RGB2GRAY);

cv::Laplacian(gray, outGray, gray.depth());

// cv::convertScaleAbs( outGray, outGray );

IplImage ipl_image(outGray);

data = (uchar*)ipl_image.imageData;

height = ipl_image.height;

width = ipl_image.width;

step = ipl_image.widthStep;

for(int i=0;i

{

for(int j=0;j

{

Iij = (int) data

[i*width+j];

Idelta = Idelta + (Iij-Iave)*(Iij-Iave);

}

}

Idelta = Idelta/(width*height);

std::cout<

}

return (Idelta > IdeltaCount) ? YES : NO;

}

demo下载地址：https://tianlin106@github.com/tianlin106/OpencvAutoTakeImage.git

三、人脸识别的扩展- (void)processImage:(cv::Mat &)image

{

cv::Mat outCopyImg;

image.copyTo(outCopyImg);

cv::cvtColor(outCopyImg, outCopyImg, CV_BGR2RGB);

if ([self isPhotoContainsFeature:MatToUIImage(outCopyImg)]) {

if ([self isPhotoIsBrightness:image] == YES) {

[self disposeCamare];

keepMatImg = outCopyImg;

UIImage * resultImage = MatToUIImage(outCopyImg);

//需要上传

[self uploadImage:resultImage];

dispatch_async(dispatch_get_main_queue(), ^{

[self.imageView removeFromSuperview];

});

}

}

}

- (BOOL)isPhotoContainsFeature:(UIImage *)image{

CIContext * context = [CIContext contextWithOptions:nil];

NSDictionary * param = [NSDictionary dictionaryWithObject:CIDetectorAccuracyHigh forKey:CIDetectorAccuracy];

CIDetector * faceDetector = [CIDetector detectorOfType:CIDetectorTypeFace context:context options:param];

//此类为Core Image Framework 中的类 ，主要用于识别某些外貌特性，以下语言为其API的描述

//An image processor that identifies notable features (such as faces and barcodes) in a still image or video.

CIImage * ciimage = [CIImage imageWithCGImage:image.CGImage];

NSArray * detectResult = [faceDetector featuresInImage:ciimage];

return detectResult.count;

}

//此方法计算图像的亮度是否符合要求

- (BOOL)isPhotoIsBrightness:(cv::Mat &)image

{

cv::Mat imageSobel;

Sobel(image, imageSobel, CV_16U, 1, 1);

//图像的平均灰度

double meanValue = 0.0;

meanValue = mean(imageSobel)[0];

if (meanValue > 1.3) {

return YES;

}

return NO;

}

四：集成主要事项：

1、导入OpenCV类目的文件的控制器必须为.mm的C++混编的文件

2、在方法命名和定义形参时，尽量避免使用关键字开头或直接使用关键字，由于OC对此项的检查不是很严格，一旦包含C++的文件以后，对关键字的检测会很强，此为需要注意的事项