Those functions do not appear to be National Instruments supplied functions. I would suggest that you contact the developer that you inherited that code from to find out where that DLL came from. What programming environment are you using and how are you acquiring the images that you are working with? There are several NI-IMAQ functions that you could use if you are working with an NI framegrabber board to obtain images.
Try downloading and installing that software and let me know if you have any additional questions.
Regards,
Scott R.
Applications Engineer
National Instruments
Scott Romine Course Development Engineer National Instruments