Measuring Distances in Plot Profiles

There is some odd behavior that happens when measuring the distance between features using Plot Profiles. This feature works as we expect when the image is a DICOM image from the CT scanner. But it doesn’t seem to work correctly for a TIFF image.


In the DICOM images, you draw a line, plot the profile and then you can measure the distance between features on the profile. The distance values match what you see if you make the measurement directly on the image. This seems correct.

TIFF Image

The steps are the same, but we need to change the scale for our TIFF images. So after setting the scale (global or otherwise), draw the line and plot the profile. Now, although the scale appears correct in the plot, the distance measured between features does not match what we measure on the image using a line. The image abscissa uses the scale we have set, but the profile distances for a line between features does not match those from the image.
The correct answer can be gotten by viewing the image properties and toggling the “global” check box. Now, follow the steps to get a profile and the measured distance will be correct - but only for the first instance of the profile you create for an image. The distances will be wrong on all subsequent profiles you create.

How does one get this feature to work correctly?

Thank you for your time.