Re: Re-performing multi-aperture measurement with same apertures
Posted by karenacollins on Jan 12, 2018; 4:44pm
URL: http://astroimagej.170.s1.nabble.com/Re-performing-multi-aperture-measurement-with-same-apertures-tp953p954.html
Hi Fabian,
There are a few options depending on exactly what you need to do.
If you want to place the apertures in the first image and then have them stay in the same place for the entire image stack, simply disable "Reposition Aperture to object centroid" in the Multi-aperture setup panel. The "Use last N apertures" option will recall the same locations for the next run. Alternatively, you can save the apertures to a file and reload them each time using menu items in the Image_Display->File menu.
If your images are not aligned and the apertures need to be in different locations for each slice of the stack, you would need to use the "Stack-Aligner" option to align the stack first, then you can place the apertures in one static location as described above.
Finally, there are two centroid options. The setting is in the Aperture Settings panel. If you enable "Use Howell Centroid Method", the centroid operation will find exactly (or nearly exactly) the same centroid position run after run (although I am surprised you are seeing significant differences using either method). The non-Howell centroid method works best for defocused images.
Hopefully, one of the above methods will provide what you need. If I misunderstand what you are needing, please post again with more details.
Karen