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@endCV_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;@endCV_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 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