C# OpenCV VideoWriter 以意想不到的颜色保存

Posted 2023-02-17

【中文标题】C# OpenCV VideoWriter 以意想不到的颜色保存

【英文标题】：C# OpenCV VideoWriter saves in unexpected colors

【发布时间】：2019-03-27 06:45:36

【问题描述】：

我正在使用 Intel Realsense RGB 摄像头在 WPF 窗口上显示实时流并将流保存到文件中。我在窗口上显示的颜色正确，但是当我保存它时，视频颜色关闭（更多紫色）。请看截图：https://ibb.co/txy9Sgd

我正在使用 EmguCV 视频编写器来保存视频。我对格式没有太多了解。我猜我对 Format24bppRgb 格式做错了什么？

private Pipeline pipeline = new Pipeline(); // Create and config the pipeline to strem color and depth frames.
private CancellationTokenSource tokenSource;
private VideoWriter writer = null;

public StartTests()

    InitializeComponent();


private void Window_Loaded(object sender, RoutedEventArgs e)

    tokenSource = new CancellationTokenSource();
    int fcc = VideoWriter.Fourcc('M', 'P', '4', 'V'); //'M', 'J', 'P', 'G'
    float fps = 15F;
    writer = new VideoWriter("testttt.mp4", fcc, fps, new System.Drawing.Size(640, 480), true);

    Config cfg = new Config();
    cfg.EnableStream(Stream.Color, 640, 480, format: Format.Rgb8);
    PipelineProfile pp = pipeline.Start(cfg);
    StartRenderFrames(pp);


private void StartRenderFrames(PipelineProfile pp)

    // Allocate bitmaps for rendring. Since the sample aligns the depth frames to the color frames, both of the images will have the color resolution
    using (VideoStreamProfile p = pp.GetStream(Stream.Color) as VideoStreamProfile)
    
        imgColor.Source = new WriteableBitmap(p.Width, p.Height, 96d, 96d, PixelFormats.Rgb24, null);
    
    Action<VideoFrame> updateColor = UpdateImage(imgColor);

    Task.Factory.StartNew(() =>
    
        while (!tokenSource.Token.IsCancellationRequested)
        
            using (FrameSet frames = pipeline.WaitForFrames()) // Wait for the next available FrameSet
            
                VideoFrame colorFrame = frames.ColorFrame.DisposeWith(frames);

                // Save frames to file here...
                System.Drawing.Bitmap ColorImg = new System.Drawing.Bitmap(colorFrame.Width, colorFrame.Height, colorFrame.Stride, System.Drawing.Imaging.PixelFormat.Format24bppRgb, colorFrame.Data);
                Image<Bgr, Byte> imageCV = new Image<Bgr, byte>(ColorImg); //Image Class from Emgu.CV
                Mat matFrame = imageCV.Mat;
                writer.Write(matFrame);

                // Render to WPF window here...
                Dispatcher.Invoke(DispatcherPriority.Render, updateColor, colorFrame);
            
        
    , tokenSource.Token);


static Action<VideoFrame> UpdateImage(Image img)

    WriteableBitmap wbmp = img.Source as WriteableBitmap;
    return new Action<VideoFrame>(frame =>
    
        using (frame)
        
            var rect = new Int32Rect(0, 0, frame.Width, frame.Height);
            wbmp.WritePixels(rect, frame.Data, frame.Stride * frame.Height, frame.Stride);
        
    );


private void Window_Closing(object sender, System.ComponentModel.CancelEventArgs e)

    tokenSource.Cancel();
    tokenSource.Dispose();
    pipeline.Stop();
    writer.Dispose();
    tokenSource = new CancellationTokenSource();

我想在保存的 .mp4 文件中看到一致的颜色，但我看到了奇怪的颜色。

注意 - 我的代码基于此示例：https://github.com/IntelRealSense/librealsense/blob/master/wrappers/csharp/cs-tutorial-2-capture/Window.xaml.cs

【参考方案1】：

OpenCV 采用 BGR 颜色格式，因此如果您将 RealSense 流格式更改为 Format.Bgra8 并将 WriteableBitmap 格式更改为 PixelFormats.Bgr24，应该没问题。

所以你应该有：

cfg.EnableStream(Stream.Color, 640, 480, format: Format.Bgr8);

和

new WriteableBitmap(p.Width, p.Height, 96d, 96d, PixelFormats.Bgr24, null);

我认为您不需要更改 System.Drawing.Bitmap 像素格式，因为您只是使用它来提供 OpenCV mat。

【讨论】：

我试图寻找您提到的这些格式，但它们在选项中不可用。你的意思是改变这些位置？ ``` imgColor.Source = new WriteableBitmap(p.Width, p.Height, 96d, 96d, PixelFormats.Rgb24, null); System.Drawing.Bitmap ColorImg = new System.Drawing.Bitmap(colorFrame.Width, colorFrame.Height, colorFrame.Stride, System.Drawing.Imaging.PixelFormat.Format24bppRgb, colorFrame.Data); ```