below is my code: i am getting an error null reference exception was unhandled on following highlighted line
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.Structure;
using Emgu.Util;
using Emgu.CV.CvEnum;
namespace CameraCapture
{
public partial class CameraCapture : Form
{
//declaring global variables
private Capture capture; //takes images from camera as image frames
private HaarCascade haar; //the viola-jones classifier (detector)
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)
{
//Read an image from hard disk at location e.g 'E:\IMAGES\'
//Image InputImg = Image.FromFile(@"E:\IMAGES\MyPic.jpg");
//Image MyImage = new Image(new Bitmap(InputImg));
//fetch the frame captured by web camera
Image ImageFrame = capture.QueryFrame();
//Detect Faces from the ImageFrame
if (ImageFrame != null) // confirm that image is valid
{
//convert the image to gray scale
Image grayframe = ImageFrame.Convert();
//detect faces from the gray-scale image and store into an array of type 'var',i.e 'MCvAvgComp[]'
var faces = grayframe.DetectHaarCascade(haar, 1.4, 4,
HAAR_DETECTION_TYPE.DO_CANNY_PRUNING,
new Size(25, 25))[0];
//draw a green rectangle on each detected face in image
foreach (var face in faces)
{
ImageFrame.Draw(face.rect, new Bgr(Color.Green), 3);
}
}
//show the image in the EmguCV ImageBox
CamImageBox.Image = ImageFrame;
//To show the image in windows forms PictureBox called pictureBox1
//pictureBox1.Image= ImageFrame.ToBitmap();
}
//btnStart_Click() function is the one that handles our "Start!" button's 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,
private void btnStart_Click(object sender, EventArgs e)
{
if (capture != null)
{
if (btnStart.Text == "Pause")
{ //if camera is getting frames then pause the capture and set button Text to
// "Resume" for resuming capture
btnStart.Text = "Resume"; //
Application.Idle -= ProcessFrame;
}
else
{
//if camera is NOT getting frames then start the capture and set button
// Text to "Pause" for pausing capture
btnStart.Text = "Pause";
Application.Idle += ProcessFrame;
}
}
}
private void ReleaseData()
{
if (capture != null)
capture.Dispose();
}
///
/// This function is the Selected Index changed event of the comboBox
/// It allows the user to select a desired camera and starts it for him/her
///
private void cbCamIndex_SelectedIndexChanged(object sender, EventArgs e)
{
//Set the camera number to the one selected via combo box
int CamNumber = -1;
CamNumber = int.Parse(cbCamIndex.Text);
//Start the selected camera
#region if capture is not created, create it now
if (capture == null)
{
try
{
capture = new Capture(CamNumber);
}
catch (NullReferenceException excpt)
{
MessageBox.Show(excpt.Message);
}
}
#endregion
//Start showing the stream from camera
btnStart_Click(sender, e);
btnStart.Enabled = true;
}
private void CameraCapture_Load(object sender, EventArgs e)
{
// adjust path to find your xml at loading
haar = new HaarCascade("haarcascade_frontalface_alt_tree.xml");
}
}
}
Jignesh TrivediPosted Jun 19, 2013, 11:00 PM
it might be grayframe object is null....
this type of error comes because of you are accessing property or methods of null object.
hope this will help you.
Pankaj PandeyPosted Jun 19, 2013, 9:28 AM
i think the data from HAAR_DETECTION_TYPE.DO_CANNY_PRUNING is not getting.