Hi all,
I wrote a vision software in VB .NET using ni ActiveX controls, now, I need more speed in a convolution function so I wrote a C dll containing the imaqConvolve function that is faster than the counterpart in ActiveX control. I call this dll from vb .net and all is OK if I acquire the image from the dll directly in Image* format.
Problem now is that the original image is available in CWIMAQIMAGE format in .NET workspace and I have to convert it in Image* format to use it in the dll. The solution I found is not fast.....do you have some suggestions? Below or
here my solution and proposal:
"
I spent the last two days in making some tests:
I built a vb .net sw and a C console application, both performing the
same task, a convolution of a 1280x1024 image with a 7x7 kernel.
I
measured with a high resolution timer the time spent by
cwimaqvision.convolute and imaqConvolve: 32ms in C and 180ms in VB .NET
!!!
At this point I built a dll in unmanaged C++ inmplementing in it
the imaqConvolve function: I call this dll with pInvoke from vb .NET
and the performance is quite the same of C console application. For
time consuming tasks I think that the dll way is good but there is a
little problem that I hope National Instruments developers can help me
to solve: actually I have to convert the CWIMAQIMAGE type in IMAGE*
type and then from IMAGE* to CWIMAQIMAGE.....to do that I used
cwimaqimage.imagetoarray in vb.net and imaqArrayToImage in
dll.....ARGGGGGGG....the array format is not compatible between .net
activex and c !!!!! I noted that in .net the bidimensional array is
saved in memory as a columns array, in C the array is created as a rows
array...so is necessary to organize memory with a for cycle. Too much
overhead.
Is it possible to have in C a imaqArrayToImage compatible function with .net array format ?
Do you have other suggestions ?
Thanks all
"
