infinitenothing

It's been a while since I've used Vision but I remember seeing some weird things with the higher bit depth images. I remember that sometimes you had to explicitly set the bit depth of the image:
http://zone.ni.com/reference/en-XX/help/370281P-01/imaqvision/imaq_image_bit_depth/
 
What pixel values are in your image? Could they just be really low? I'm guessing the gradient or rainbow pallets aren't helping

Something like this but with better reference handling?
 

You need to convert your array to a list of coordinates and pass it to the linear fit function.