iOS OpenCV的回调"processImage"分辨率与ImageView不匹配

ios opencv's callback "processImage" resolution not matched with the ImageView

本文关键字：ImageView 不匹配 分辨率 processImage 回调 iOS OpenCV      更新时间：2023-10-16

我在iOS上使用过opencv3，我使用以下代码捕获视频并处理图像

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

以及回调

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

但我得到的图像是640行480列的尺寸，这很奇怪。因为如果我把图像放在"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的垫在主行中。我需要把它处理成480*640的垫子，有什么解决方案吗？

我也试着转换它，但当它显示在ImageView上时看起来很奇怪，也许opencv的内部隐含地旋转了垫子？

虽然看起来你已经修复了它，但我感觉你以后也会遇到类似的问题。以下是如何避免所有这些问题（我只是粘贴另一个答案中的代码，该答案恰好也适用于这种情况）：

"你没有具体说明有问题的窗口是视图还是图层，或者是实时视频还是保存到文件中。你也没有具体说明视频是通过OpenCV录制的，还是通过其他方式录制的。

因此，我为每一个偶然事件都包含了代码片段；如果你熟悉OpenCV和iOS视图编程的基础知识，你应该清楚地知道你应该使用什么（顺便说一句，在我的情况下，我使用了所有的）：

- (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，你必须知道放在哪里。如果你想不出来，请告诉我。

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