c++ - ios opencv 的回调 "processImage"分辨率与 ImageView 不匹配

Question

我在 iOS 上使用过 opencv3，我使用下面的代码来捕获视频和处理图像

videoCamera = [[CvVideoCamera alloc] initWithParentView:_imageView];
videoCamera.defaultAVCaptureDevicePosition = AVCaptureDevicePositionBack;
videoCamera.delegate = self;
videoCamera.defaultAVCaptureSessionPreset = AVCaptureSessionPreset640x480;
videoCamera.defaultAVCaptureVideoOrientation = AVCaptureVideoOrientationPortrait;
videoCamera.defaultFPS = 30;

和回调

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

但是我得到的图像是 640 行和 480 列的尺寸，这很奇怪。因为如果我将图像放入“640 宽 * 480 高”的 ImageView 中，它就非常适合。图像垫应该是 480 行 * 640 列，因为 opencv 的垫是行主要的。我需要将其处理为 480 * 640 垫子，有什么解决方案吗？

我也尝试过转置它，但是当它显示在 ImageView 上时看起来很奇怪，也许 opencv 的内部已经隐式地旋转了垫子？

Answer 1

虽然看起来您已修复它，但我感觉您以后会遇到类似的问题。这是避免所有这些问题的方法(我只是从另一个答案中粘贴代码，该答案恰好也适用于这种情况):

“您没有具体说明所讨论的窗口是 View 还是层，或者它是实时视频还是保存到文件中。您也没有具体说明视频是通过 OpenCV 录制的还是通过是用另一种方式记录的。

因此，我包含了每种意外事件的代码片段；如果您熟悉 OpenCV 和 iOS View 编程的基础知识，那么您应该使用什么应该是显而易见的(顺便说一句，在我的例子中，我使用了所有这些):

- (void)viewDidLayoutSubviews {
    [super viewDidLayoutSubviews];

    switch ([UIDevice currentDevice].orientation) {
        case UIDeviceOrientationPortraitUpsideDown:
            self.videoCamera.defaultAVCaptureVideoOrientation = AVCaptureVideoOrientationPortraitUpsideDown;
            break;
        case UIDeviceOrientationLandscapeLeft:
            self.videoCamera.defaultAVCaptureVideoOrientation = AVCaptureVideoOrientationLandscapeLeft;
            break;
        case UIDeviceOrientationLandscapeRight:
            self.videoCamera.defaultAVCaptureVideoOrientation = AVCaptureVideoOrientationLandscapeRight;
            break;
        default:
            self.videoCamera.defaultAVCaptureVideoOrientation = AVCaptureVideoOrientationPortrait;
            break;
    }

    [self refresh];
}

- (void)processImage:(cv::Mat &)mat {

    if (self.videoCamera.running) {
        switch (self.videoCamera.defaultAVCaptureVideoOrientation) {
            case AVCaptureVideoOrientationLandscapeLeft:
            case AVCaptureVideoOrientationLandscapeRight:
                // The landscape video is captured upside-down.
                // Rotate it by 180 degrees.
                cv::flip(mat, mat, -1);
                break;
            default:
                break;
        }
    }


- (void)convertBlendSrcMatToWidth:(int)dstW height:(int)dstH {

    double dstAspectRatio = dstW / (double)dstH;

    int srcW = originalBlendSrcMat.cols;
    int srcH = originalBlendSrcMat.rows;
    double srcAspectRatio = srcW / (double)srcH;
    cv::Mat subMat;
    if (srcAspectRatio < dstAspectRatio) {
        int subMatH = (int)(srcW / dstAspectRatio);
        int startRow = (srcH - subMatH) / 2;
        int endRow = startRow + subMatH;
        subMat = originalBlendSrcMat.rowRange(startRow, endRow);
    } else {
        int subMatW = (int)(srcH * dstAspectRatio);
        int startCol = (srcW - subMatW) / 2;
        int endCol = startCol + subMatW;
        subMat = originalBlendSrcMat.colRange(startCol, endCol);
    }
    cv::resize(subMat, convertedBlendSrcMat, cv::Size(dstW, dstH), 0.0, 0.0, cv::INTER_LANCZOS4);



- (int)imageWidth {
    AVCaptureVideoDataOutput *output = [self.captureSession.outputs lastObject];
    NSDictionary *videoSettings = [output videoSettings];
    int videoWidth = [[videoSettings objectForKey:@"Width"] intValue];
    return videoWidth;
}

- (int)imageHeight {
    AVCaptureVideoDataOutput *output = [self.captureSession.outputs lastObject];
    NSDictionary *videoSettings = [output videoSettings];
    int videoHeight = [[videoSettings objectForKey:@"Height"] intValue];
    return videoHeight;
}

- (void)updateSize {
    // Do nothing.
}

- (void)layoutPreviewLayer {
    if (self.parentView != nil) {

        // Center the video preview.
        self.customPreviewLayer.position = CGPointMake(0.5 * self.parentView.frame.size.width, 0.5 * self.parentView.frame.size.height);

        // Find the video's aspect ratio.
        CGFloat videoAspectRatio = self.imageWidth / (CGFloat)self.imageHeight;

        // Scale the video preview while maintaining its aspect ratio.
        CGFloat boundsW;
        CGFloat boundsH;
        if (self.imageHeight > self.imageWidth) {
            if (self.letterboxPreview) {
                boundsH = self.parentView.frame.size.height;
                boundsW = boundsH * videoAspectRatio;
            } else {
                boundsW = self.parentView.frame.size.width;
                boundsH = boundsW / videoAspectRatio;
            }
        } else {
            if (self.letterboxPreview) {
                boundsW = self.parentView.frame.size.width;
                boundsH = boundsW / videoAspectRatio;
            } else {
                boundsH = self.parentView.frame.size.height;
                boundsW = boundsH * videoAspectRatio;
            }
        }
        self.customPreviewLayer.bounds = CGRectMake(0.0, 0.0, boundsW, boundsH);
    }
}


- (void)processImage:(cv::Mat &)mat {

    if (self.videoCamera.running) {
        switch (self.videoCamera.defaultAVCaptureVideoOrientation) {
            case AVCaptureVideoOrientationLandscapeLeft:
            case AVCaptureVideoOrientationLandscapeRight:
                // The landscape video is captured upside-down.
                // Rotate it by 180 degrees.
                cv::flip(mat, mat, -1);
                break;
            default:
                break;
        }
    }


- (void)convertBlendSrcMatToWidth:(int)dstW height:(int)dstH {

    double dstAspectRatio = dstW / (double)dstH;

    int srcW = originalBlendSrcMat.cols;
    int srcH = originalBlendSrcMat.rows;
    double srcAspectRatio = srcW / (double)srcH;
    cv::Mat subMat;
    if (srcAspectRatio < dstAspectRatio) {
        int subMatH = (int)(srcW / dstAspectRatio);
        int startRow = (srcH - subMatH) / 2;
        int endRow = startRow + subMatH;
        subMat = originalBlendSrcMat.rowRange(startRow, endRow);
    } else {
        int subMatW = (int)(srcH * dstAspectRatio);
        int startCol = (srcW - subMatW) / 2;
        int endCol = startCol + subMatW;
        subMat = originalBlendSrcMat.colRange(startCol, endCol);
    }
    cv::resize(subMat, convertedBlendSrcMat, cv::Size(dstW, dstH), 0.0, 0.0, cv::INTER_LANCZOS4);



- (int)imageWidth {
    AVCaptureVideoDataOutput *output = [self.captureSession.outputs lastObject];
    NSDictionary *videoSettings = [output videoSettings];
    int videoWidth = [[videoSettings objectForKey:@"Width"] intValue];
    return videoWidth;
}

- (int)imageHeight {
    AVCaptureVideoDataOutput *output = [self.captureSession.outputs lastObject];
    NSDictionary *videoSettings = [output videoSettings];
    int videoHeight = [[videoSettings objectForKey:@"Height"] intValue];
    return videoHeight;
}

- (void)updateSize {
    // Do nothing.
}

- (void)layoutPreviewLayer {
    if (self.parentView != nil) {

        // Center the video preview.
        self.customPreviewLayer.position = CGPointMake(0.5 * self.parentView.frame.size.width, 0.5 * self.parentView.frame.size.height);

        // Find the video's aspect ratio.
        CGFloat videoAspectRatio = self.imageWidth / (CGFloat)self.imageHeight;

        // Scale the video preview while maintaining its aspect ratio.
        CGFloat boundsW;
        CGFloat boundsH;
        if (self.imageHeight > self.imageWidth) {
            if (self.letterboxPreview) {
                boundsH = self.parentView.frame.size.height;
                boundsW = boundsH * videoAspectRatio;
            } else {
                boundsW = self.parentView.frame.size.width;
                boundsH = boundsW / videoAspectRatio;
            }
        } else {
            if (self.letterboxPreview) {
                boundsW = self.parentView.frame.size.width;
                boundsH = boundsW / videoAspectRatio;
            } else {
                boundsH = self.parentView.frame.size.height;
                boundsW = boundsH * videoAspectRatio;
            }
        }
        self.customPreviewLayer.bounds = CGRectMake(0.0, 0.0, boundsW, boundsH);
    }
}

这里有很多东西，你必须知道把它放在哪里。如果您不明白，请告诉我。