Using caliper to measure the diameter of an irregular shape

[lordhol1]

hello everyone

I'm a beginner with labview and i'm working on a project about  measuring the diameter of an appendix on an image. 

I already created VI with vision assistant to process the image, but get an error when ever I try to used the caliper to do the measurment.

error: not enough are available at this step of the script to perform goemetric functions.

NB: I have attached a copy of my IV and image below.

[Jacobson-ni]

Try right-clicking on the output image display on the front panel and selecting Palette > Binary. This should change the display to what you see in the Vision Assistant. By default, thresholding will return a grayscale image with pixel values of either 0 or 1 so, alternitively, you could open up the second Vision Assistant VI in LabVIEW and input a constant Replace Value of 255 into the IMAQ Threshold function which would return a grayscale image with pixel values of either 0 or 255.