calibrate distance in pixel to real world measurment unit

[L_K]

I want to calibrate a distance in pixel (I don't have coordinates that make the distance). I looked at the calibration VIs, but there isn't any VI that allow me to convert distance in pixel to real world measurement. So I want to calculate the distance in real world units by using the distance in pixel. Is there anyway to calculate the distance in real world measurement unit if I know how many pixel in X and Y axis (my X Step is not equal to Y Step) is equal to the unit in real world?

[dcourtri]

This is possible. The IMAQ Set Simple Calibration.vi allows you to input a grid descriptor which is the number of real world units per pixel. This is a very simple calibration and does not take into consideration lens or perspective distortion. There are also VI's which will convert between pixel and real world values. Hope this helps. Have a good one.

[L_K]

Does this method allow me to calibrate only the points in pixel to real world or also the distance in pixel? The distance I am talking about is not the distance from the lens to the object, it's the distance that I measure from a point to another point in the image-that's why the distance is in pixel. What I want to do is to change the distance from pixel to real world without using any point information (the points that make the distance)(becuase I don't have one).

[dcourtri]

The distance that is being calibrated is between two points on an image. Actually what happens is that you give a grid descriptor stating the pixel to real world value ratio. This creates a map for the whole image that way you can get the corresponding real world values which allows for the calculation of the real world distance between any two points.

[L_K]

I use IMAQ find best circle.vi (or some name familiar to this - I don't remember the name quite exactly) This VI finds circles in the greyscale image and it gives center coordinates of the circles, area and radius in pixel. To change the radius in pixel to micrometer, how do I go from here? I don't want to use any caliper tool because my program is very complicated and don't want to add any mess to it.