Posted by
Monique Vasseur on
Jul 18, 2006; 2:22pm
URL: http://imagej.273.s1.nabble.com/Optical-artefact-removal-tp3702076p3702081.html
Hi
Hi Jacqueline,
Looking at your image, I think you have sort of a light leek somewhere in your optical . Do you have 2 light sources on your microscope? Or one port that is not light proof? I had that problem with a fluorescence Nikon upright microscope when we where acquiring images in transmitted light and that the mercury lamp was on (at that time we where missing an empty filter cube in the filter turret) but we could avoid the diffraction effect by closing the manual fluorescence shutter on the microscope.
But for your actual images, I guess you could easily do a shading correction by:
1- getting a background image (a spot on your slide but out of the specimen area) with the same parameters of exposure time and binning than your specimen image
2- than you divide your specimen image by the background image to get your shading corrected image.
Monique Vasseur
Microscopie et imagerie
Département de biochimie
Université de Montréal
tél. (514) 343-6111 poste 5148
-----Message d'origine-----
De : ImageJ Interest Group [mailto:
[hidden email]] De la part de Jacqui Ross
Envoyé : 18 juillet 2006 02:41
À :
[hidden email]
Objet : Optical artefact removal
Dear All,
I have had an enquiry from someone from another Department who has an
artefact affecting their imaging which looks like a diffraction effect
(e.g. Newton rings) when doing transmitted light microscopy.
I had a look at their microscope and camera system and even when Koehler
illumination is set up properly, you still get this effect. The
microscope is a rather old Nikon inverted microscope with a Coolpix
attached. The objectives, (phase contrast), are not infinity corrected
and I'm assuming that there is also a problem with the tube length for
the camera. The rings are there irrespective whether specimens are on
glass or in plastic dishes. I don't think much can be done optically
(correct me if I'm wrong) but I wondered if some image processing could
help.
My ImageJ question is this:
Is it possible to use some kind of image processing (e.g. image
subtraction) to remove this artifact? I have tried a few things out
(e.g. Image calculator, rolling ball) without much success so far.
I have posted 2 images at the following address:
http://www.health.auckland.ac.nz/biru/exptal_images/index.html There are
also links to larger images although the original images are even larger
than these.
Please note that I do know that these images are appalling! I asked one
of the students to send me one image with tissue (glass slide) and one
without at the same focal plane and this is what I got! I don't think
they set up the microscope very well. However, you can see the rings
clearly on both images so I hope they will inspire someone to suggest a
solution.
I would be very pleased to hear of any potential solutions.
Cheers,
Jacqui.
Jacqueline Ross
Biomedical Imaging Research Unit
School of Medical Sciences
Faculty of Medical & Health Sciences
The University of Auckland
Private Bag 92019
Auckland, NEW ZEALAND
Tel: 64 9 373 7599 Ext 87438
Fax: 64 9 373 7484
http://www.health.auckland.ac.nz/biru/<
http://www.health.auckland.ac.nz/biru/>