"Region of Interest change" event on IMAQ image display control

[TiTou]

It would really help to be able to catch an "Region of Interest change" event on an image display control!

And of course the ability to discard it from within the event structure.

Thanks in advance!

[AristosQueue (NI)]

ROI? What is that?

[TiTou]

Sorry... Region of Interest, like image display control it is mostly used by people using Vision Development Module (VDM).

[AristosQueue (NI)]

Ah. Would that be a bad coupling of implementation with interface? The control that displays the image is a bad point for another part of your program to listen to for value changes... These aren't user inputs, but the results of some other part of your program rendering a value. It would be far better programming practice for you to have a ROI comparison that fires a user event than to rely on the picture actually being rendered.

[drjdpowell]

Actually, the ROI is a User input.  In fact, though it is displayed on the image rendered, I don't think it is dependant on it.  The image display indicator can be viewed as a "Region of Interest" User control.

[AristosQueue (NI)]

I'm guessing you're not referring to the 2D Picture Control?

[drjdpowell]

I'm talking about the "IMAQ Image" control, which I assumed is what TiTou was talking about.  It has User adjustable ROI, but no events for such.  For comparison, an XY-graph does have a set of events for when the User adjusts its cursors (which are often used to define a region of interest).

[TiTou]

Indeed, I'm not talking about 2 picture control but the "Display image control" that comes with Vision Development module.

For a vision application, in some cases the regions of interest are defined automatically by the software because their position must follow the objects you track, but in some other case you want the user to select the region he wants and for that matter it yould make life easier to have a "ROI change" event for the IMAQ image display control , then we would no longer have to pull on the ROI to compare to the previous (ROI is a property of the IMAQ image display control).

[X.]

Looks similar to this suggestion (stated differently though) and this discussion.

BTW, there should be an IMAQ specific Idea Exchange forum. That would save Aristos Q some embarrassment...:-)

[TiTou]

"there should be an IMAQ specific Idea Exchange forum."

Oh yes! 

[Intaris]

Teh Vision toolkit needs so many updates it really would warrant a seperate idea exchange.

As for this idea, absolutely.  If anypone has ever tried doing some really "serious" Vision rpogramming, they will have hit this barrier and scratched thair heeads thinking "I must be missing something, surely that is already implemented".  Alas.....