Hello taywatch,
You could use a property node for the image control on the front panel in order to extract the region of interest referring to a line drawn on the image for other purposes. I have attached two images to demonstrate this. To get the property node I have used here, right click on the image control and select
Create >> Property Node >> ROI. I then overlayed this ROI onto the original image. The second attachment shows you the final image shown on the front panel after drawing a line on the first image.
I hope this helps.
Vivek Nath
National Instruments
Applications Engineer
Machine Vision