Why is image to array (vision call in C++) not then displaying my array in my code?

[Kari H]

I am adding to the example program found at C:\Program Files\National Instruments\Vision\Examples\MSVC\Load And Display.  I need to convert the image to an array and have used the function imagetoarray to do so. My array does not display on the screen, but the prompt caused by the system pause to "press any key" does.  Can anyone tell me why or what I am doing wrong in my code?  Thanks! See code below:

    unsigned char *array;
    unsigned int row, col;
    int columns, rows;
   
    /* Get the array of pixel values*/
    array = (unsigned char*)imaqImageToArray (image, IMAQ_NO_RECT, &columns, &rows);
   
    /* Display the results */
    cout << "\n The Array \n";
    for (row = 0; row < rows; ++row) {
        for (col = 0; col < columns; ++col) {
            cout << &array[row,col] << endl;
           cout << "\n";
        }
    }
    system ("PAUSE");
    /* Cleanup */
    imaqDispose (array);

[Maclean]

Hi Kari,

Thank you for posting on the NI forums!  In C++, the syntax for reference arrays is array[dimension_1][dimension_2] instead of array[dimension_1,dimension_2]. I am surprised that your compiler did not throw an error.  While this isn't an error so much as a warning, but in your for loops you increment the column and row indexes with ++row and ++col.   This means that the variables are incremented before the loop is run, so you will actually miss the first element in each column and row.  Finally, you are printing out a line brake after every element, so your image will be displayed as one pixel on every other line, and a blank line in between which makes the read out twice as long.  My suggested changes are below:

/* Display the results */
    cout << "\n The Array (row,column) = (" << rows << "," << columns << ")\n";
    for (row = 0; row < rows; row++) {
        for (col = 0; col < columns; col++) {
            cout << "(" << row << "," << col << "): " << &array[row][col] << endl;
        }
    }

Regards,

[Kari H]

Hi,
Thank you so much for the suggestions and for pointing out my errors.  I implemented them but it seems that something is still awry. 
Do you know why I am getting this error: '1>..\Load And DisplayDlg1.cpp(199) : error C2109: subscript requires array or pointer type'

referring to this portion of code: 'cout << "(" << row << "," << col << "): " << &array[row][col] << endl;'?
I tried removing the ampersand against my better judgement, but still got the same error.

Thank you in advance,
Kari

[Maclean]

Hi Kari,

You are right in guessing that the ampersand should be removed.  The ampersand is a reference operator, which makes the compiler point to the numerical value of the address of the variable array rather than the actual data in array.  I think that error results from your call to imaqImageToArray.  The function definition is as follows:

void* imaqImageToArray(const Image* image, Rect rect, int* columns, int* rows);

So when you call the function with:

array = (unsigned char*)imaqImageToArray (image, IMAQ_NO_RECT, &columns, &rows);

You are assigning a void pointer to array.  What you want to call instead, is:

imaqImageToArray ((Image*)array, IMAQ_NO_RECT, &columns, &rows);

That will point array to the image array that is created in the imaqImageToArray function.

I hope this does the trick!

[Maclean]

Hi Kari,

I should revise my previous post.  You were actually correct in your code:

array = (unsigned char*)imaqImageToArray (image, IMAQ_NO_RECT, &columns, &rows);

Because the return type of the image is arbitrary (U8, U16 etc.), and must be cast manually.  The problem is actually in indexing the array. The array the image is returned as a 1D array, rather then 2D. The proper code would be:

cout << "(" << row << "," << col << "): " << array[row*columns + col] << endl;

Regards,

[Kari H]

Thank you for those corrections.  The code is running without error, but the array is not being shown on the screen (press any key still is though).  I am including the new code with changes and then the many warnings that I get.  Is there any reason that the array may not show up that you can think of?  Is my memory allocation off?

Thanks so much,
Kari

CODE:

void CLoadAndDisplayDlg::OnBnClickedButton1()
{
    //-----------
    /****************************************************************************/
/*  Converts image into an array. These values are */
/*  displayed for the user on the Front Panel, then the array is disposed.  */
/****************************************************************************/

    unsigned char *array;
    unsigned int row, col;
    int columns, rows;
    
    /* Get the array of pixel values inside the rect */
    array = (unsigned char*)imaqImageToArray (image, IMAQ_NO_RECT, &columns, &rows);
    
    /* Display the results */
    cout << "\n The Array (row,column) = (" << rows << "," << columns << ")\n";
    for (row = 0; row < rows; row++) {
        for (col = 0; col < columns; col++) {
             cout << "(" << row << "," << col << "): " << array[row*columns + col] << endl;
           cout << "\n";
        }
    }
    system ("PAUSE");
    /* Cleanup */
    imaqDispose (array);

}


Warnings that I get:
'LoadImageArray.exe': Loaded 'C:\Documents and Settings\debug\LoadImageArray.exe', Symbols loaded.
'LoadImageArray.exe': Loaded 'C:\WINDOWS\system32\ntdll.dll', No symbols loaded.
'LoadImageArray.exe': Loaded 'C:\WINDOWS\system32\kernel32.dll', No symbols loaded.
'LoadImageArray.exe': Loaded 'C:\WINDOWS\system32\user32.dll', No symbols loaded.
'LoadImageArray.exe': Loaded 'C:\WINDOWS\system32\gdi32.dll', No symbols loaded.
'LoadImageArray.exe': Loaded 'C:\WINDOWS\system32\shlwapi.dll', No symbols loaded.
'LoadImageArray.exe': Loaded 'C:\WINDOWS\system32\advapi32.dll', No symbols loaded.
'LoadImageArray.exe': Loaded 'C:\WINDOWS\system32\rpcrt4.dll', No symbols loaded.
'LoadImageArray.exe': Loaded 'C:\WINDOWS\system32\msvcrt.dll', No symbols loaded.
'LoadImageArray.exe': Loaded 'C:\WINDOWS\system32\NIVision.dll', Binary was not built with debug information.
'LoadImageArray.exe': Loaded 'C:\WINDOWS\system32\NIVisSvc.dll', Binary was not built with debug information.
'LoadImageArray.exe': Loaded 'C:\WINDOWS\system32\ole32.dll', No symbols loaded.
'LoadImageArray.exe': Loaded 'C:\WINDOWS\system32\oleaut32.dll', No symbols loaded.
'LoadImageArray.exe': Loaded 'C:\WINDOWS\system32\setupapi.dll', No symbols loaded.
'LoadImageArray.exe': Loaded 'C:\WINDOWS\system32\ws2_32.dll', No symbols loaded.
'LoadImageArray.exe': Loaded 'C:\WINDOWS\system32\ws2help.dll', No symbols loaded.
'LoadImageArray.exe': Loaded 'C:\WINDOWS\system32\netapi32.dll', No symbols loaded.
'LoadImageArray.exe': Loaded 'C:\WINDOWS\system32\comdlg32.dll', No symbols loaded.
'LoadImageArray.exe': Loaded 'C:\WINDOWS\system32\comctl32.dll', No symbols loaded.
'LoadImageArray.exe': Loaded 'C:\WINDOWS\system32\shell32.dll', No symbols loaded.
'LoadImageArray.exe': Loaded 'C:\WINDOWS\system32\winmm.dll', No symbols loaded.
'LoadImageArray.exe': Loaded 'C:\WINDOWS\system32\winspool.drv', No symbols loaded.
'LoadImageArray.exe': Loaded 'C:\WINDOWS\system32\olepro32.dll', No symbols loaded.
'LoadImageArray.exe': Loaded 'C:\WINDOWS\system32\ddraw.dll', No symbols loaded.
'LoadImageArray.exe': Loaded 'C:\WINDOWS\system32\dciman32.dll', No symbols loaded.
'LoadImageArray.exe': Loaded 'C:\WINDOWS\system32\version.dll', No symbols loaded.
'LoadImageArray.exe': Loaded 'C:\WINDOWS\system32\oleacc.dll', No symbols loaded.
'LoadImageArray.exe': Loaded 'C:\WINDOWS\system32\msvcp60.dll', No symbols loaded.
'LoadImageArray.exe': Loaded 'C:\Program Files\Google\Google Desktop Search\GoogleDesktopNetwork3.dll', No symbols loaded.
'LoadImageArray.exe': Unloaded 'C:\Program Files\Google\Google Desktop Search\GoogleDesktopNetwork3.dll'
'LoadImageArray.exe': Loaded 'C:\WINDOWS\WinSxS\x86_Microsoft.Windows.Common-Controls_6595b64144ccf1df_6.0.2600.2982_x-ww_ac3f9c03\comctl32.dll', No symbols loaded.
'LoadImageArray.exe': Loaded 'C:\WINDOWS\system32\icmp.dll', No symbols loaded.
'LoadImageArray.exe': Loaded 'C:\WINDOWS\system32\iphlpapi.dll', No symbols loaded.
'LoadImageArray.exe': Loaded 'C:\WINDOWS\system32\mswsock.dll', No symbols loaded.
'LoadImageArray.exe': Loaded 'C:\WINDOWS\system32\dnsapi.dll', No symbols loaded.
'LoadImageArray.exe': Loaded 'C:\WINDOWS\system32\winrnr.dll', No symbols loaded.
'LoadImageArray.exe': Loaded 'C:\WINDOWS\system32\wldap32.dll', No symbols loaded.
'LoadImageArray.exe': Loaded 'C:\WINDOWS\system32\rasadhlp.dll', No symbols loaded.
'LoadImageArray.exe': Loaded 'C:\WINDOWS\system32\apphelp.dll', No symbols loaded.
'LoadImageArray.exe': Loaded 'C:\WINDOWS\system32\clbcatq.dll', No symbols loaded.
'LoadImageArray.exe': Loaded 'C:\WINDOWS\system32\comres.dll', No symbols loaded.
'LoadImageArray.exe': Loaded 'C:\WINDOWS\system32\cscui.dll', No symbols loaded.
'LoadImageArray.exe': Loaded 'C:\WINDOWS\system32\cscdll.dll', No symbols loaded.
'LoadImageArray.exe': Loaded 'C:\WINDOWS\system32\browseui.dll', No symbols loaded.
'LoadImageArray.exe': Loaded 'C:\WINDOWS\system32\ntshrui.dll', No symbols loaded.
'LoadImageArray.exe': Loaded 'C:\WINDOWS\system32\atl.dll', No symbols loaded.
'LoadImageArray.exe': Loaded 'C:\WINDOWS\system32\userenv.dll', No symbols loaded.
'LoadImageArray.exe': Loaded 'C:\WINDOWS\system32\uxtheme.dll', No symbols loaded.
'LoadImageArray.exe': Loaded 'C:\WINDOWS\system32\shdocvw.dll', No symbols loaded.
'LoadImageArray.exe': Loaded 'C:\WINDOWS\system32\crypt32.dll', No symbols loaded.
'LoadImageArray.exe': Loaded 'C:\WINDOWS\system32\msasn1.dll', No symbols loaded.
'LoadImageArray.exe': Loaded 'C:\WINDOWS\system32\cryptui.dll', No symbols loaded.
'LoadImageArray.exe': Loaded 'C:\WINDOWS\system32\wintrust.dll', No symbols loaded.
'LoadImageArray.exe': Loaded 'C:\WINDOWS\system32\imagehlp.dll', No symbols loaded.
'LoadImageArray.exe': Loaded 'C:\WINDOWS\system32\wininet.dll', No symbols loaded.
'LoadImageArray.exe': Loaded 'C:\WINDOWS\system32\riched20.dll', No symbols loaded.
'LoadImageArray.exe': Unloaded 'C:\WINDOWS\system32\riched20.dll'
'LoadImageArray.exe': Unloaded 'C:\WINDOWS\system32\browseui.dll'
'LoadImageArray.exe': Unloaded 'C:\WINDOWS\system32\shdocvw.dll'
'LoadImageArray.exe': Unloaded 'C:\WINDOWS\system32\cryptui.dll'
'LoadImageArray.exe': Unloaded 'C:\WINDOWS\system32\wininet.dll'
'LoadImageArray.exe': Unloaded 'C:\WINDOWS\system32\wintrust.dll'
'LoadImageArray.exe': Unloaded 'C:\WINDOWS\system32\imagehlp.dll'
'LoadImageArray.exe': Unloaded 'C:\WINDOWS\system32\crypt32.dll'
'LoadImageArray.exe': Unloaded 'C:\WINDOWS\system32\msasn1.dll'
First-chance exception at 0x7c812a5b in LoadImageArray.exe: Microsoft C++ exception: GRLIBError_enum at memory location 0x0012c4ec..
First-chance exception at 0x7c812a5b in LoadImageArray.exe: Microsoft C++ exception: GRLIBError_enum at memory location 0x0012c544..
First-chance exception at 0x7c812a5b in LoadImageArray.exe: Microsoft C++ exception: GRLIBError_enum at memory location 0x0012c4ec..
First-chance exception at 0x7c812a5b in LoadImageArray.exe: Microsoft C++ exception: GRLIBError_enum at memory location 0x0012c544..
The thread 'Win32 Thread' (0x234) has exited with code 0 (0x0).
The thread 'Win32 Thread' (0x15e0) has exited with code 0 (0x0).
The thread 'Win32 Thread' (0x1440) has exited with code 0 (0x0).
The program '[3824] LoadImageArray.exe: Native' has exited with code 0 (0x0).

[Maclean]

Hi Kari,

When are the warnings occurring exactly? Is it on the line with:

cout << "(" << row << "," << col << "): " << array[row*columns + col] << endl;

Try debugging the code and watching the array pointer. Is it a pointing to a valid memory location? You should be able to step through the code line by line in the debugger and watch each variable's value as the code executes. If this still doesn't clear the problem up, can you attach your code so I can execute it?

Thank you,

[Kari H]

Hi Maclean,
To be specific about the warnings that I am getting:
This first set comes up to the point of the dialog box appearing where you can select browse directory, and load image, convert to array, and quit.

'LoadImageArray.exe': Loaded 'C:\Documents and Settings\Kari Haxhinasto\My Documents\Kari\Work\Visual Studio 2005\Projects\C_Code_From_LbV\LoadImageArray\LoadImageArray\debug\LoadImageArray.exe', Symbols loaded.
'LoadImageArray.exe': Loaded 'C:\WINDOWS\system32\ntdll.dll', No symbols loaded.
'LoadImageArray.exe': Loaded 'C:\WINDOWS\system32\kernel32.dll', No symbols loaded.
'LoadImageArray.exe': Loaded 'C:\WINDOWS\system32\user32.dll', No symbols loaded.
'LoadImageArray.exe': Loaded 'C:\WINDOWS\system32\gdi32.dll', No symbols loaded.
'LoadImageArray.exe': Loaded 'C:\WINDOWS\system32\shlwapi.dll', No symbols loaded.
'LoadImageArray.exe': Loaded 'C:\WINDOWS\system32\advapi32.dll', No symbols loaded.
'LoadImageArray.exe': Loaded 'C:\WINDOWS\system32\rpcrt4.dll', No symbols loaded.
'LoadImageArray.exe': Loaded 'C:\WINDOWS\system32\msvcrt.dll', No symbols loaded.
'LoadImageArray.exe': Loaded 'C:\WINDOWS\system32\NIVision.dll', Binary was not built with debug information.
'LoadImageArray.exe': Loaded 'C:\WINDOWS\system32\NIVisSvc.dll', Binary was not built with debug information.
'LoadImageArray.exe': Loaded 'C:\WINDOWS\system32\ole32.dll', No symbols loaded.
'LoadImageArray.exe': Loaded 'C:\WINDOWS\system32\oleaut32.dll', No symbols loaded.
'LoadImageArray.exe': Loaded 'C:\WINDOWS\system32\setupapi.dll', No symbols loaded.
'LoadImageArray.exe': Loaded 'C:\WINDOWS\system32\ws2_32.dll', No symbols loaded.
'LoadImageArray.exe': Loaded 'C:\WINDOWS\system32\ws2help.dll', No symbols loaded.
'LoadImageArray.exe': Loaded 'C:\WINDOWS\system32\netapi32.dll', No symbols loaded.
'LoadImageArray.exe': Loaded 'C:\WINDOWS\system32\comdlg32.dll', No symbols loaded.
'LoadImageArray.exe': Loaded 'C:\WINDOWS\system32\comctl32.dll', No symbols loaded.
'LoadImageArray.exe': Loaded 'C:\WINDOWS\system32\shell32.dll', No symbols loaded.
'LoadImageArray.exe': Loaded 'C:\WINDOWS\system32\winmm.dll', No symbols loaded.
'LoadImageArray.exe': Loaded 'C:\WINDOWS\system32\winspool.drv', No symbols loaded.
'LoadImageArray.exe': Loaded 'C:\WINDOWS\system32\olepro32.dll', No symbols loaded.
'LoadImageArray.exe': Loaded 'C:\WINDOWS\system32\ddraw.dll', No symbols loaded.
'LoadImageArray.exe': Loaded 'C:\WINDOWS\system32\dciman32.dll', No symbols loaded.
'LoadImageArray.exe': Loaded 'C:\WINDOWS\system32\version.dll', No symbols loaded.
'LoadImageArray.exe': Loaded 'C:\WINDOWS\system32\oleacc.dll', No symbols loaded.
'LoadImageArray.exe': Loaded 'C:\WINDOWS\system32\msvcp60.dll', No symbols loaded.
'LoadImageArray.exe': Loaded 'C:\Program Files\Google\Google Desktop Search\GoogleDesktopNetwork3.dll', No symbols loaded.
'LoadImageArray.exe': Unloaded 'C:\Program Files\Google\Google Desktop Search\GoogleDesktopNetwork3.dll'
'LoadImageArray.exe': Loaded 'C:\WINDOWS\WinSxS\x86_Microsoft.Windows.Common-Controls_6595b64144ccf1df_6.0.2600.2982_x-ww_ac3f9c03\comctl32.dll', No symbols loaded.
'LoadImageArray.exe': Loaded 'C:\WINDOWS\system32\icmp.dll', No symbols loaded.
'LoadImageArray.exe': Loaded 'C:\WINDOWS\system32\iphlpapi.dll', No symbols loaded.
'LoadImageArray.exe': Loaded 'C:\WINDOWS\system32\mswsock.dll', No symbols loaded.
'LoadImageArray.exe': Loaded 'C:\WINDOWS\system32\dnsapi.dll', No symbols loaded.
'LoadImageArray.exe': Loaded 'C:\WINDOWS\system32\winrnr.dll', No symbols loaded.
'LoadImageArray.exe': Loaded 'C:\WINDOWS\system32\wldap32.dll', No symbols loaded.
'LoadImageArray.exe': Loaded 'C:\WINDOWS\system32\rasadhlp.dll', No symbols loaded.

When you select browse:

'LoadImageArray.exe': Loaded 'C:\WINDOWS\system32\apphelp.dll', No symbols loaded.
'LoadImageArray.exe': Loaded 'C:\WINDOWS\system32\clbcatq.dll', No symbols loaded.
'LoadImageArray.exe': Loaded 'C:\WINDOWS\system32\comres.dll', No symbols loaded.
'LoadImageArray.exe': Loaded 'C:\WINDOWS\system32\cscui.dll', No symbols loaded.
'LoadImageArray.exe': Loaded 'C:\WINDOWS\system32\cscdll.dll', No symbols loaded.
'LoadImageArray.exe': Loaded 'C:\WINDOWS\system32\browseui.dll', No symbols loaded.
'LoadImageArray.exe': Loaded 'C:\WINDOWS\system32\ntshrui.dll', No symbols loaded.
'LoadImageArray.exe': Loaded 'C:\WINDOWS\system32\atl.dll', No symbols loaded.
'LoadImageArray.exe': Loaded 'C:\WINDOWS\system32\userenv.dll', No symbols loaded.
'LoadImageArray.exe': Loaded 'C:\WINDOWS\system32\uxtheme.dll', No symbols loaded.
'LoadImageArray.exe': Loaded 'C:\WINDOWS\system32\shdocvw.dll', No symbols loaded.
'LoadImageArray.exe': Loaded 'C:\WINDOWS\system32\crypt32.dll', No symbols loaded.
'LoadImageArray.exe': Loaded 'C:\WINDOWS\system32\msasn1.dll', No symbols loaded.
'LoadImageArray.exe': Loaded 'C:\WINDOWS\system32\cryptui.dll', No symbols loaded.
'LoadImageArray.exe': Loaded 'C:\WINDOWS\system32\wintrust.dll', No symbols loaded.
'LoadImageArray.exe': Loaded 'C:\WINDOWS\system32\imagehlp.dll', No symbols loaded.
'LoadImageArray.exe': Loaded 'C:\WINDOWS\system32\wininet.dll', No symbols loaded.
'LoadImageArray.exe': Loaded 'C:\WINDOWS\system32\riched20.dll', No symbols loaded.
'LoadImageArray.exe': Unloaded 'C:\WINDOWS\system32\riched20.dll'
'LoadImageArray.exe': Loaded 'C:\WINDOWS\system32\xpsp2res.dll', Binary was not built with debug information.
'LoadImageArray.exe': Loaded 'C:\Program Files\Adobe\Acrobat 7.0\ActiveX\pdfshell.dll', No symbols loaded.
'LoadImageArray.exe': Loaded 'C:\WINDOWS\system32\shimgvw.dll', No symbols loaded.
'LoadImageArray.exe': Loaded 'C:\WINDOWS\WinSxS\x86_Microsoft.Windows.GdiPlus_6595b64144ccf1df_1.0.2600.2180_x-ww_522f9f82\GdiPlus.dll', No symbols loaded.
The thread 'Win32 Thread' (0xb44) has exited with code 1 (0x1).
'LoadImageArray.exe': Unloaded 'C:\WINDOWS\system32\shimgvw.dll'
'LoadImageArray.exe': Unloaded 'C:\WINDOWS\WinSxS\x86_Microsoft.Windows.GdiPlus_6595b64144ccf1df_1.0.2600.2180_x-ww_522f9f82\GdiPlus.dll'
'LoadImageArray.exe': Unloaded 'C:\Program Files\Adobe\Acrobat 7.0\ActiveX\pdfshell.dll'
'LoadImageArray.exe': Unloaded 'C:\WINDOWS\system32\browseui.dll'
'LoadImageArray.exe': Unloaded 'C:\WINDOWS\system32\shdocvw.dll'
'LoadImageArray.exe': Unloaded 'C:\WINDOWS\system32\cryptui.dll'
'LoadImageArray.exe': Unloaded 'C:\WINDOWS\system32\wininet.dll'
'LoadImageArray.exe': Unloaded 'C:\WINDOWS\system32\wintrust.dll'
'LoadImageArray.exe': Unloaded 'C:\WINDOWS\system32\imagehlp.dll'
'LoadImageArray.exe': Unloaded 'C:\WINDOWS\system32\crypt32.dll'
'LoadImageArray.exe': Unloaded 'C:\WINDOWS\system32\msasn1.dll'
The thread 'Win32 Thread' (0xaa4) has exited with code 0 (0x0).
The thread 'Win32 Thread' (0x10f4) has exited with code 0 (0x0).
The thread 'Win32 Thread' (0x4d0) has exited with code 0 (0x0).


Then when you select load image:
these errors appear as the image appears

First-chance exception at 0x7c812a5b in LoadImageArray.exe: Microsoft C++ exception: GRLIBError_enum at memory location 0x0012c4ec..
First-chance exception at 0x7c812a5b in LoadImageArray.exe: Microsoft C++ exception: GRLIBError_enum at memory location 0x0012c544..
First-chance exception at 0x7c812a5b in LoadImageArray.exe: Microsoft C++ exception: GRLIBError_enum at memory location 0x0012c4ec..

Then, when you select convert to array:
no warnings appear


Then, upon selecting quit:

The thread 'Win32 Thread' (0x668) has exited with code 0 (0x0).
The program '[4652] LoadImageArray.exe: Native' has exited with code 0 (0x0).
First-chance exception at 0x7c812a5b in LoadImageArray.exe: Microsoft C++ exception: GRLIBError_enum at memory location 0x0012c544..


The frustrating thing is that the program runs without showing the array.  Something is obviously wrong, but hard to pinpoint since I get no errors.  I will attach the project here which will hopefully be of help.  Thanks so much,
Kari

[Kari H]

Hi again,
So, to answer your question, no, these warnings do not appear with the code:
cout << "(" << row << "," << col << "): " << array[row*columns + col] << endl;

That is part of the confusion, since it seems to be a larger problem.
I notice, when I try to open the project I just posted, it doesn't allow you to, but that you can open individual files.  I will try to fix this, but am not sure how to change access privelages.  Is there a simple fix to this?
Thanks so much,
Kari

[Maclean]

Hi Kari,

I am looking over your code. In the mean time, try running a simple example that ships with NI-Vision. If the example runs without error, then we know that your NI-Vision and IMAQ functions are properly installed and working.

Regards,