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CIDetector 边缘识别

作者：繁依Fanyi0 | 2024-03-13 15:34:01

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cidetectortyperectangle识别不出

CoreImage下CIDetector.h自带了四种识别功能

  1. / * 人脸识别 */
  2. CORE_IMAGE_EXPORT NSString* const CIDetectorTypeFace NS_AVAILABLE(10_7, 5_0);
  3.  
  4. / * 矩形边缘识别 */
  5. CORE_IMAGE_EXPORT NSString* const CIDetectorTypeRectangle NS_AVAILABLE(10_10, 8_0);
  6.  
  7. /* 二维码识别 */
  8. CORE_IMAGE_EXPORT NSString* const CIDetectorTypeQRCode NS_AVAILABLE(10_10, 8_0);
  9.  
  10. /* 文本识别 */
  11. #if __OBJC2__
  12. CORE_IMAGE_EXPORT NSString* const CIDetectorTypeText NS_AVAILABLE(10_11, 9_0);
  13. 复制代码

接下来用CIDetectorTypeRectangle对图片的矩形状边缘进行识别，效果图如下 （Demo链接文章底部已给出）

部分代码：

  • 初始化一个高精度的识别器
  1. // 高精度边缘识别器
  2. - (CIDetector *)highAccuracyRectangleDetector
  3. {
  4.     static CIDetector *detector = nil;
  5.     static dispatch_once_t onceToken;
  6.     dispatch_once(&onceToken, ^
  7.                   {
  8.                       detector = [CIDetector detectorOfType:CIDetectorTypeRectangle context:nil options:@{CIDetectorAccuracy : CIDetectorAccuracyHigh}];
  9.                   });
  10.     return detector;
  11. }
  12. 复制代码
  • 调用照相机捕获摄像头图像
  1. NSArray *possibleDevices = [AVCaptureDevice devicesWithMediaType:AVMediaTypeVideo];
  2.     AVCaptureDevice *device = [possibleDevices firstObject];
  3.     if (!device) return;
  4.     
  5.     _imageDedectionConfidence = 0.0;
  6.     
  7.     AVCaptureSession *session = [[AVCaptureSession alloc] init];
  8.     self.captureSession = session;
  9.     [session beginConfiguration];
  10.     self.captureDevice = device;
  11.     
  12.     NSError *error = nil;
  13.     AVCaptureDeviceInput* input = [AVCaptureDeviceInput deviceInputWithDevice:device error:&error];
  14.     session.sessionPreset = AVCaptureSessionPresetPhoto;
  15.     [session addInput:input];
  16.     
  17.     AVCaptureVideoDataOutput *dataOutput = [[AVCaptureVideoDataOutput alloc] init];
  18.     [dataOutput setAlwaysDiscardsLateVideoFrames:YES];
  19.     [dataOutput setVideoSettings:@{(id)kCVPixelBufferPixelFormatTypeKey:@(kCVPixelFormatType_32BGRA)}];
  20.     [dataOutput setSampleBufferDelegate:self queue:dispatch_get_main_queue()];
  21.     [session addOutput:dataOutput];
  22.     
  23.     self.stillImageOutput = [[AVCaptureStillImageOutput alloc] init];
  24.     [session addOutput:self.stillImageOutput];
  25.     
  26.     AVCaptureConnection *connection = [dataOutput.connections firstObject];
  27.     [connection setVideoOrientation:AVCaptureVideoOrientationPortrait];
  28. 复制代码
  • 还需要有个显示已捕获图像的容器
  1.  self.context = [[EAGLContext alloc] initWithAPI:kEAGLRenderingAPIOpenGLES2];
  2.     GLKView *view = [[GLKView alloc] initWithFrame:self.bounds];
  3.     view.autoresizingMask = UIViewAutoresizingFlexibleWidth | UIViewAutoresizingFlexibleHeight;
  4.     view.translatesAutoresizingMaskIntoConstraints = YES;
  5.     view.context = self.context;
  6.     view.contentScaleFactor = 1.0f;
  7.     view.drawableDepthFormat = GLKViewDrawableDepthFormat24;
  8.     [self insertSubview:view atIndex:0];
  9.     _glkView = view;
  10.     glGenRenderbuffers(1, &_renderBuffer);
  11.     glBindRenderbuffer(GL_RENDERBUFFER, _renderBuffer);
  12.     
  13.     //图像将绘制进_coreImageContext内
  14.     _coreImageContext = [CIContext contextWithEAGLContext:self.context];
  15.     [EAGLContext setCurrentContext:self.context];
  16. 复制代码
  • 遵循AVCaptureVideoDataOutputSampleBufferDelegate代理，捕获到图像之后，会调用以下方法
  1. -(void)captureOutput:(AVCaptureOutput *)captureOutput didOutputSampleBuffer:(CMSampleBufferRef)sampleBuffer fromConnection:(AVCaptureConnection *)connection
  2. 复制代码

调用CIDetector进行识别，并且获取最大不规则四边形

  1. // 从缓冲区中获取CIImage
  2. CVPixelBufferRef pixelBuffer = (CVPixelBufferRef)CMSampleBufferGetImageBuffer(sampleBuffer);
  3. CIImage *image = [CIImage imageWithCVPixelBuffer:pixelBuffer];
  4.  // 用高精度边缘识别器 识别特征
  5. NSArray <CIFeature *>*features = [[self highAccuracyRectangleDetector] featuresInImage:image];
  6. // 选取特征列表中最大的不规则四边形
  7.  _borderDetectLastRectangleFeature = [self biggestRectangleInRectangles:features];
  8. 复制代码
  • 识别到边缘之后使用CAShapeLayer将边缘绘制并显示
  1. // 绘制边缘检测图层
  2. - (void)drawBorderDetectRectWithImageRect:(CGRect)imageRect topLeft:(CGPoint)topLeft topRight:(CGPoint)topRight bottomLeft:(CGPoint)bottomLeft bottomRight:(CGPoint)bottomRight
  3. {
  4.     
  5.     if (!_rectOverlay) {
  6.         _rectOverlay = [CAShapeLayer layer];
  7.         _rectOverlay.fillRule = kCAFillRuleEvenOdd;
  8.         _rectOverlay.fillColor = [UIColor colorWithRed:73/255.0 green:130/255.0 blue:180/255.0 alpha:0.4].CGColor;
  9.         _rectOverlay.strokeColor = [UIColor whiteColor].CGColor;
  10.         _rectOverlay.lineWidth = 5.0f;
  11.     }
  12.     if (!_rectOverlay.superlayer) {
  13.         self.layer.masksToBounds = YES;
  14.         [self.layer addSublayer:_rectOverlay];
  15.     }
  16.  
  17.     // 将图像空间的坐标系转换成uikit坐标系
  18.     TransformCIFeatureRect featureRect = [self transfromRealRectWithImageRect:imageRect topLeft:topLeft topRight:topRight bottomLeft:bottomLeft bottomRight:bottomRight];
  19.     
  20.     // 边缘识别路径
  21.     UIBezierPath *path = [UIBezierPath new];
  22.     [path moveToPoint:featureRect.topLeft];
  23.     [path addLineToPoint:featureRect.topRight];
  24.     [path addLineToPoint:featureRect.bottomRight];
  25.     [path addLineToPoint:featureRect.bottomLeft];
  26.     [path closePath];
  27.     // 背景遮罩路径
  28.     UIBezierPath *rectPath  = [UIBezierPath bezierPathWithRect:CGRectMake(-5,
  29.                                                                           -5,
  30.                                                                           self.frame.size.width + 10,
  31.                                                                           self.frame.size.height + 10)];
  32.     [rectPath setUsesEvenOddFillRule:YES];
  33.     [rectPath appendPath:path];
  34.     _rectOverlay.path = rectPath.CGPath;
  35. }
  36. 复制代码

即可显示出实时识别的效果了

  • 最后拍照之后的裁剪，使用该滤镜将识别出的不规则四边形转换成矩形，即可转换成正正方方的矩形了
  1. /// 将任意四边形转换成长方形
  2. - (CIImage *)correctPerspectiveForImage:(CIImage *)image withFeatures:(CIRectangleFeature *)rectangleFeature
  3. {
  4.     NSMutableDictionary *rectangleCoordinates = [NSMutableDictionary new];
  5.     rectangleCoordinates[@"inputTopLeft"] = [CIVector vectorWithCGPoint:rectangleFeature.topLeft];
  6.     rectangleCoordinates[@"inputTopRight"] = [CIVector vectorWithCGPoint:rectangleFeature.topRight];
  7.     rectangleCoordinates[@"inputBottomLeft"] = [CIVector vectorWithCGPoint:rectangleFeature.bottomLeft];
  8.     rectangleCoordinates[@"inputBottomRight"] = [CIVector vectorWithCGPoint:rectangleFeature.bottomRight];
  9.     return [image imageByApplyingFilter:@"CIPerspectiveCorrection" withInputParameters:rectangleCoordinates];
  10. }
  11. 复制代码

// TODO : 识别出边缘之后，可以手动设置边缘范围

Demo地址： github传送门：https://github.com/madaoCN/MADRectDetect 好心人点下Star呗

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