GetImagePixelPointer in IMAQ Vision hangs while trying to get a pixel pointer.

Question

I have written several dll functions to do specific image processing. I have been successfully calling these dlls for some time. In rewriting my code to parallelize some activity, a single instance has come up where GetImagePixelPointer starts to execute but never returns. The instance appears to be related to a single image. I have looked backwards in my code and I am pretty sure that I unmap the pixel pointer from the previous time it gets used.
Does anyone have any advice? What would cause GetImagePixelPointer to hang in the Map mode?

Answer 1

Hey Matt,
You mentioned things were working fine until you parallelized the code (you made multiple threads I assume). You also mentioned when you tried reproducing the problem, it worked fine. It sounded like if you took out the call to GetPixelValue in your original code that didn't work, it worked (is this correct). One of the problems I could see that having multiple threads might cause is if you create the image in a different thread than where you try and get the pixel pointer. The different threads have their own place on the heap and one thread's memory allocations may not be available to other threads.
If you're still having problems, see if you can make a small snippet to reproduce (you will probably have to use multiple threads to reproduce this problem)
Hope
this helps,
Brad Buchanan
National Instruments