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I am taking photo using AVCaptureStillImageOutput, AVCaptureSession, AVCaptureVideoPreviewLayer and display it in UIImageView. Its work properly.

But, After display image in UIImage. I am detecting faces using OpenCV from that displayed image.

It detect, but it returns the rotated image. I am not use any code for rotate the image. Its automatically rotate the image.

I want to stop rotating.

Here is my code.

+ (UIImage *) opencvFaceDetect:(UIImage *)originalImage  {
    cvSetErrMode(CV_ErrModeParent);

    IplImage *image = [self CreateIplImageFromUIImage:originalImage];

    // Scaling down
    IplImage *small_image = cvCreateImage(cvSize(image->width/2,image->height/2), IPL_DEPTH_8U, 3);
    cvPyrDown(image, small_image, CV_GAUSSIAN_5x5);
    int scale = 2;

    // Load XML
    NSString *path = [[NSBundle mainBundle] pathForResource:@"haarcascade_frontalface_default" ofType:@"xml"];
    CvHaarClassifierCascade* cascade = (CvHaarClassifierCascade*)cvLoad([path cStringUsingEncoding:NSASCIIStringEncoding], NULL, NULL, NULL);
    CvMemStorage* storage = cvCreateMemStorage(0);

    // Detect faces and draw rectangle on them
    CvSeq* faces = cvHaarDetectObjects(small_image, cascade, storage, 1.2f, 2, CV_HAAR_DO_CANNY_PRUNING, cvSize(20, 20), cvSize(100, 100));
    cvReleaseImage(&small_image);

    NSLog(@"found %d faces in image", faces->total);

    // Create canvas to show the results
    CGImageRef imageRef = originalImage.CGImage;
    CGColorSpaceRef colorSpace = CGColorSpaceCreateDeviceRGB();
    CGContextRef contextRef = CGBitmapContextCreate(NULL, originalImage.size.width, originalImage.size.height, 8, originalImage.size.width * 4,
                                                    colorSpace, kCGImageAlphaPremultipliedLast|kCGBitmapByteOrderDefault);
    CGContextDrawImage(contextRef, CGRectMake(0, 45, originalImage.size.width, originalImage.size.height), imageRef);

    CGContextSetLineWidth(contextRef, 4);
    CGContextSetRGBStrokeColor(contextRef, 0.0, 0.0, 1.0, 0.5);

    // Draw results on the iamge
    for(int i = 0; i < faces->total; i++) {
        NSAutoreleasePool * pool = [[NSAutoreleasePool alloc] init];

        // Calc the rect of faces
        CvRect cvrect = *(CvRect*)cvGetSeqElem(faces, i);
        CGRect face_rect = CGContextConvertRectToDeviceSpace(contextRef, 
                                CGRectMake(cvrect.x * scale, cvrect.y * scale, cvrect.width * scale, cvrect.height * scale));
        CGContextStrokeRect(contextRef, face_rect);

        [pool release];
    }

    UIImage *returnImage = [UIImage imageWithCGImage:CGBitmapContextCreateImage(contextRef)];
    CGContextRelease(contextRef);
    CGColorSpaceRelease(colorSpace);

    cvReleaseMemStorage(&storage);
    cvReleaseHaarClassifierCascade(&cascade);

    return returnImage;
}

Here is the Screen shots

1) Image for before calling face detection method Image before face detection method called

2) Image for after calling face detection method Image after face detection method called

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1 回答 1

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您是否使用 UIImageJPEGRepresentation 来获取这些图像？如果是这样，那么您可能对此感兴趣：

http://blog.logichigh.com/2008/06/05/uiimage-fix/

--> "UIImageJPEGRepresentation()，将 UIImage 转换为 JPEG 的最简单（唯一？）方法使用底层 CGImage，并忽略您的 UIImage imageOrientation，因此无论拍摄照片时的相机位置如何，导出的 JPEG 将始终定向在横向或右侧模式下，最终得到需要旋转的图片。”

这暗示即使您不使用此功能，imageOrientation使用UIImage.

于 2011-06-10T14:38:45.820 回答