Posted by
Joel Sheffield on
Jul 18, 2006; 2:15pm
URL: http://imagej.273.s1.nabble.com/Optical-artefact-removal-tp3702076p3702085.html
Jacqui,
This is, unfortunately, an optical artifact of the coolpix cameras.
We have seen this primarily with the Coolpix 995, but I understand
that it occurs in others as well. Our solution is to take a
background image and subtract it from the image of the sample.
However, this is a particularly tricky thing to do with color images.
Since we see this problem most often with DIC images, we just convert
to greyscale and work with that. If color is important, you might
consider separating the images into R,G,B images, processing each of
them, and then reassembling with RGB merge, or take a look at the
Color Balance program by Gabriel Landini.
(
http://www.dentistry.bham.ac.uk/landinig/software/software.html)
I haven't used it, but the design does make sense.
The best way to eliminate the artifact, I'm afraid, is to get a
different camera.
Joel
Date sent: Tue, 18 Jul 2006 18:40:55 +1200
Send reply to: ImageJ Interest Group <
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From: Jacqui Ross <
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Subject: Optical artefact removal
To:
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> 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/>
>
>
Joel B. Sheffield, Ph.D
Department of Biology
Temple University
Philadelphia, PA 19122
Voice: 215 204 8839
e-mail:
[hidden email]