c# - 如何将emgu相机捕获的图像保存在文件夹中并检索

Question

如何将 emgu CV 相机捕获的图像保存在文件夹中并检索。每当我试图保存空引用异常时都会出错。

using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Linq;
using System.Text;
using System.Windows.Forms;
using Emgu.CV;
using Emgu.CV.UI;
using Emgu.CV.Util;
using Emgu.CV.Structure;

namespace camerapart2
{
    public partial class Form1 : Form
    {
        private Capture capture;
        private bool captureinprogress;
        public Form1()
        {
            InitializeComponent();
        }

        private void ProcessFrame(object sender, EventArgs arg)

        Image<Bgr, Byte> ImageFrame = capture.QueryFrame();
        cameraimage.Image = ImageFrame;
        pictureBox1.Image = ImageFrame.ToBitmap();
        ImageFrame.Save(@"E:\MyPic.jpg");

        private void btnStart_Click(object sender, EventArgs e)
        {
            if (capture == null)
            {
                try
                {
                    capture = new Capture();
                }
                catch (NullReferenceException excpt)
                {
                    MessageBox.Show(excpt.Message);
                }
            }

            if (capture != null)
            {
                if (captureinprogress)
                {  //if camera is getting frames then stop the capture and set button Text
                    // "Start" for resuming capture
                    btnstart.Text = "Start!"; //
                    Application.Idle -= ProcessFrame;
                }
                else
                {
                    //if camera is NOT getting frames then start the capture and set button
                    // Text to "Stop" for pausing capture
                    btnstart.Text = "Stop";
                    Application.Idle += ProcessFrame;
                }

                captureinprogress = !captureinprogress;
            }
        }

        private void ReleaseData()
        {
            if (capture != null)
                capture.Dispose();
        }
    }
}

在这两行中，我收到了 nullreference 错误：

pictureBox1.Image = ImageFrame.ToBitmap();
ImageFrame.Save(@"E:\MyPic.jpg");

Answer 1

我使用了 emguCV 的 ImageBox 而不是原生 C# 的 pictureBox，并在表单上添加了一个按钮 btnSave

namespace CameraCapture
{
    public partial class CameraCapture : Form
    {
        //declaring global variables
        private Capture capture;        //takes images from camera as image frames
        private bool captureInProgress;
        private bool saveToFile;

        public CameraCapture()
        {
            InitializeComponent();
        }
        //------------------------------------------------------------------------------//
        //Process Frame() below is our user defined function in which we will create an EmguCv 
        //type image called ImageFrame. capture a frame from camera and allocate it to our 
        //ImageFrame. then show this image in ourEmguCV imageBox
        //------------------------------------------------------------------------------//
        private void ProcessFrame(object sender, EventArgs arg)
        {
            Image<Bgr, Byte> ImageFrame = capture.QueryFrame();
            CamImageBox.Image = ImageFrame;
            if (saveToFile)
            {
                ImageFrame.Save(@"D:\MyPic.jpg");
                saveToFile = !saveToFile;
            }
        }

        //btnStart_Click() function is the one that handles our "Start!" button' click 
        //event. it creates a new capture object if its not created already. e.g at first time
        //starting. once the capture is created, it checks if the capture is still in progress,
        //if so the
        private void btnStart_Click(object sender, EventArgs e)
        {
            #region if capture is not created, create it now
            if (capture == null)
            {
                try
                {
                    capture = new Capture();
                }
                catch (NullReferenceException excpt)
                {
                    MessageBox.Show(excpt.Message);
                }
            }
            #endregion

            if (capture != null)
            {
                if (captureInProgress)
                {  //if camera is getting frames then stop the capture and set button Text
                    // "Start" for resuming capture
                    btnStart.Text = "Start!"; //
                    Application.Idle -= ProcessFrame;
                }
                else
                {
                    //if camera is NOT getting frames then start the capture and set button
                    // Text to "Stop" for pausing capture
                    btnStart.Text = "Stop";
                    Application.Idle += ProcessFrame;
                }

                captureInProgress = !captureInProgress;
            }
        }

        private void ReleaseData()
        {
            if (capture != null)
                capture.Dispose();
        }

        private void btnSave_Click(object sender, EventArgs e)
        {
            saveToFile = !saveToFile;
        }
    }
}

Answer 2

这个主题很旧，但如果你想使用 emguCV 的 ImageBox，你可以使用这个代码

   private void ProcessFrame(object sender, EventArgs arg)
    {
        Mat frame = new Mat();
        capture.Retrieve(frame);
        CamImageBox.Image = frame;
    }