Polygon ROI, flip horizontal

Hi everyone,

I’m trying to flip a polygon ROI shape about the horizontal axis to create a mirrored shape. My goal is to measure an image of a symmetrical region so I would like to duplicate the free-hand polygon shape for both sides (with the same area). As a follow-up, is the intensity measurement (Analyze -> Measure) taken in units/area? If mirroring the shape is not possible, then maybe the area of the shape doesn’t matter if the measurement is normalized by area. The same shape would still be ideal!

Thank you!

Welcome to the forum, @onhitchcock!

You can do this using the Edit > Selection > Scale… command, e.g. by scaling with a factor of -1 in x and +1 in y direction to flip horizontally:

run("Scale... ", "x=-1 y=1 centered");

This depends on what measurements you select in Analyze > Set Measurements…:

  • Mean gray value will be normalized to the area
  • Integrated density will be the sum of intensities and therefore depend on the area

Have a look at the user guide for details.


Thank you so much for your help, @imagejan!