Re: calibration in photomicroscopy
Re: calibration in photomicroscopy
- Subject: Re: calibration in photomicroscopy
- From: Johannes Hoffstadt <email@hidden>
- Date: Tue, 01 Feb 2005 12:20:16 +0100
Hi,
depends on what your goal is. If you want to treat the camera
as a stand-alone part, creating ICC profiles day after day and
comparing them is a way to go. In fact, you wouldn't really
need to create profiles, just shooting a test target and comparing
RGB values might be good enough to document the stability
of the camera - if the lighting conditions are constant enough.
I think that the key point - and difficulty - is here, in the
lighting setup for those recurring test shoots of the target,
regardless whether it's reflective or transmissive. So you'd
need some means to control that - yet another measurement
device probably - and you're almost done.
To go on, you'd need "only" some image processing toolkit to
average and downsample the rgb values before comparison.
I heard ImageJ mentioned on the ECI discussion list some
time ago. This way you could avoid profiling and profile
comparison software altogether.
But if the goal is to describe the system as a whole, as it
captures microscopic images, and to render them more or
less as seen...
Based on our experience with applying ICC technology
to microscopy, I can recommend a spectral approach
involving targets, light sources, optics, and viewing
conditions, to arrive at a profile for the whole system.
Like Jon said, there are undoubtedly somewhat special
spectra involved there (fluorescent material, tissue, ...).
Photographic target materials are certainly a starting point,
but can turn out to be a bad choice for ICC profiling
due to camera metamerism. Then you need custom
spectral targets - not something you can buy off the shelf...
Hanno Hoffstadt
---
Dr. Johannes Hoffstadt
Color Solutions Software
Kirchstrasse 5
D-89081 Ulm, Germany
+49 731 3886660
www.basiccolor.de
On Jan 28, 2005, at 09:06 AM, Jon Meyer wrote:
Hi Kurt -
There are several considerations. In concept, you could shoot a target
with a traditional lens and create a profile with basICColor dCam. When
mounting the camera to a scope, one would need to take into account the
neutrality of the apochromatic lens/coatings and allow consideration
for fluorescein or polarized images. There is no truly scientific
approach to these accommodations. Getting the CCD profile right will
put you within the same range as traditional transparency, however.
- Jon Meyer (RBP)
GrafixGear
8 West Glen Avenue
Ridgewood, NJ 07450
(201) 447-1510
email@hidden
http://www.GrafixGear.Com
On Jan 27, 2005, at 12:35 PM, Kurt Fleschner wrote:
I’m currently working to get a digital camera system for
photomicroscopy set up in my microbiology lab. Because we’re an
FDA/ISO regulated lab, we need to be able to show that the camera is
working correctly and has been calibrated on a regular schedule. The
system we’re looking at getting uses ICC profiles to ensure color from
slide to screen, so generating an ICC profile then comparing it to the
manufactures profile, or something like an IT8.7 target for
microscopes, would work for that. I know it’s possible to get deltaE
for a particular color with some profiling software, but can I
generate something like a deltaE for the whole target? Is there
software on the market for Windows that already does this, or can a
sampling of some colors be entered into an excel sheet and an average
taken? I’d appreciate any ideas people have on the subject.
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