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properly delete pointer - hopefully a quickie

Posted on 2007-11-16
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Last Modified: 2012-08-14
The loop below is toggled by a "preview" button. It show the images just fine, but it runs my memory up fast because if I put the line "cvReleaseImage(&pimage_copy) anywhere to release the memory, I get a passing null pointer even though I think I am destroying pointers as I create them. How do I reconcile? Should  I use smart pointers?


while (CameraStatusInst.Start_Button_Status(false, false))
	{
     IplImage* pimage_copy = contour_image;
 
                                    if (pimage_copy != NULL)
                                        {
                                         int key=0;
                                         cvNamedWindow("Mouse Vision", 1);
                                         cvShowImage("Mouse Vision", pimage_copy);
                                         key = cvWaitKey(20);
                                        //cvReleaseImage(&pimage_copy)    <-------------works when commented out
                                        }
                                        else
                                        {
                                        cvReleaseImage(&pimage_copy);
                                        }
 
 
    }

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Question by:Wanderinglazyeye
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8 Comments
 
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by:jkr
jkr earned 300 total points
ID: 20299404
Well, how are you initializing 'contour_image'? If you aren't using 'cvCloneImage()', there is no need to release it. See the demo code at http://softintegration.com/products/thirdparty/opencv/demos/
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by:Jaime Olivares
ID: 20299510
try with:
while (CameraStatusInst.Start_Button_Status(false, false))
{
     IplImage* pimage_copy = cvCloneImage(contour_image);
 
    if (pimage_copy != NULL)
    {
          int key=0;
          cvNamedWindow("Mouse Vision", 1);
          cvShowImage("Mouse Vision", pimage_copy);
          key = cvWaitKey(20);
          cvReleaseImage(&pimage_copy)
    }
}
    

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Expert Comment

by:itsmeandnobodyelse
ID: 20300036
>>>> cvReleaseImage(&pimage_copy)
you pass the 'address' of pimage_copy to cvReleaseImage. So cvReleaseImage takes a IplImage** ?? That is strange beside cvReleaseImage would expect an array of IplImage pointers rather than a single pointer.

>>>> while (CameraStatusInst.Start_Button_Status(false, false))
>>>> {
>>>>     IplImage* pimage_copy = contour_image;

I can't see how that in that while loop you ever would get a pimage_copy == NULL. Even then, why do you call cvReleaseImage(&pimage_copy); with the address of a NULL pointer. What do you expect from that?

I would guess the above loop would fail in the second iteration cause I can't see how contour_image could get a different value (or NULL) in the meantime.

Regards, Alex

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LVL 11

Assisted Solution

by:Deepu Abraham
Deepu Abraham earned 300 total points
ID: 20301870
Hi there,

IplImage* pimage_copy = contour_image;  ---> Seems like this is not filling the correct values here..(it may not be null but some junk values)

Could you be able to check what is happening inide the function cvReleaseImage()

Best Regards,
DeepuAbrahamK



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Author Comment

by:Wanderinglazyeye
ID: 20302052
Its filling the correct values - the preview window opens up, and the expected images are seen. I removed the loop (pimage_copy == NULL), it works fine. yeah my brain farted.

IplImage* pimage_copy = cvCloneImage(contour_image);
Tried this and releasing it, get run time errors.

Problem is a memory leak when I open the preview window and stops when I close it. It jumps by 10k/second (about) until program crashes. I preview the images by using the sharing image  solution shown in another EE topic that was solved earlier.  My preview code is a thread launched from a GUI event.

Would it be helpful to anyone to post the entire thread?
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LVL 86

Assisted Solution

by:jkr
jkr earned 300 total points
ID: 20302078
Well, how are you creating 'clone_image' right now?
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Accepted Solution

by:
itsmeandnobodyelse earned 900 total points
ID: 20303792
>>>> Would it be helpful to anyone to post the entire thread?
Yes, and maybe you can tell what is the idea behind the while loop? Or did you drop the loop?  
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Author Comment

by:Wanderinglazyeye
ID: 20386975
I dropped the loop. In fact, I dropped the threads. I took your idea about the evaluating whether threads were necessary, and simply made two program versions. One with threads, one without. What I found was that the version without thread BLAZED. Still, it provided a learning experience.

Thanks ItsMe

WLE
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