Particle Analysis given in pixel units instead of user calibrated units.

[morseman]

I have calibrated an image using the "Image>>Calibration from Image" method. The resulting image is successfully calibrated in user calibrated inch units that was validated by correct line measurements using the Image>>Measure line tool. However, in both Binary>>Particle Analysis and Image>>Measure, the areas and other measurements are given in pixel units instead of the expected and desired user calibrated units. If I use the simple calibration method the results are given in the desired units. I created the calibration image using the simple calibration method and have attached the resulting template file. Also attached is a test image in which I wish to measure the holes appearing in t
he plate after I threshold and remove boarders. Any suggestions?

[nestor-sg]

Dear Sr.,

The Area of the Image>>Measure function is not supposed to be given in "user-defined" units, only the length, I believe this is the reason why even though you have calibrated the image you will still see the area in pixels, but the length in user units. It is strange for me why you mention that in simple calibration you will get the area in user units, I did the test here and I still get the same results. The Help file of Vision Builder for the Measure function states that length is given in user units (if calibrated) and the area just in pixels.

I also did the calibration and corrected the image using a grid of dots, then I went to particle analysis (in binary) and the measurements are given in my user defined units. Make sure that you are selecting the me
asurements marked as for example Area(units) and not just Area, since when it has the "(units)" it means it is going to give the result in user defined units.

I apologize that nobody else answered this question. If you need prompt assistance please contact us via www.ni.com/ask for direct mail or phone assistance.

Regards,

Nestor Sanchez
IMAQ/Motion Support
National Instruments