Overlay convex hull outline

[rouven84]

Hello there,

I'm quite new to LabView.

I'd like to overlay the outline of a particle's convex hull to the original image to see both, the convex hull AND the original image.

Can anybody help me out with this?

[BruceAmmons]

Here's a way to do it.  There may be easier ways, but this should work.

Start with your original binary image.  Call this ORIGINAL.

Perform the convex hull operation with a new destination image to preserve the original image.  Call this HULL.

Perform a binary dilate command on the new image with a new destination image.  Call this DILATE.

Subtract HULL from DILATE to get the outline of the hull.  You could also use XOR.  Call this OUTLINE.

Multiply OUTLINE by 2 to make it a different binary value.

Use OR to combine OUTLINE and ORIGINAL.  This will look pretty good using the binary palette to display it.

Bruce

[rouven84]

Thanks for your reply!
I'm going to try it. But I've got one more question:

I already found a similar solution for my problem yesterday, where the outline was somehow written to a ROI and then overlayed. But I'm trying to overlay the snapped picture of the camera with the convex hull outline, but somehow it didn't work this way.

[BruceAmmons]

You could probably use overlay bitmap instead of OR on the last step.  In this case, you would need to multiply by 255 instead of 2 so that the binary image is visible.

Bruce