Imaging particle analysis: Difference between revisions

Revision as of 18:38, 2 January 2014

Revision as of 18:39, 2 January 2014

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The basic process by which imaging particle analysis is carried out is as follows:

# A digital camera captures an image of the [[field of view]] in the optical system.

# A gray scale [[Thresholding (image processing)|thresholding]] process is used to perform [[Image segmentation#Thresholding|image segmentation]], segregating out the particles from the background, creating a [[binary image]] of each particle.<ref name=Gonzalez>{{cite book|last=Gonzalez|first=Rafael C.|title=Digital Image Processing|year=2002|publisher=Pearson Education|isbn=8178086298|pages=595-611595–611|coauthors=Woods, Richard E.}}</ref><ref name="Sankur2004">{{cite journal|last1=Sankur|first1=Bulent|title=Survey over image thresholding techniques and quantitative performance evaluation|journal=Journal of Electronic Imaging|volume=13|issue=1|year=2004|pages=146|issn=1017-9909|doi=10.1117/1.1631315}}</ref> <ref>{{cite journal|title=A Threshold Selection Method from Gray-Level Histograms|journal=IEEE Transactions on Systems, Man, and Cybernetics|volume=9|issue=1|year=1979|pages=62–66|issn=0018-9472|doi=10.1109/TSMC.1979.4310076}}</ref>

# [[Digital image processing]] techniques are used to perform [[image analysis]] operations, resulting in morphological and grey-scale measurements to be stored for each particle.<ref name="CarterYan2005">{{cite journal|last1=Carter|first1=R M|last2=Yan|first2=Y|title=Measurement of particle shape using digital imaging techniques|journal=Journal of Physics: Conference Series|volume=15|year=2005|pages=177–182|issn=1742-6588|doi=10.1088/1742-6596/15/1/030}}</ref>

# The measurements saved for each particle are then used to generate image population statistics<ref>{{cite web|last=Pouli|first=T.|title=Image Statistics and their Applications in Computer Graphics (2010)|url=http://www.cs.bris.ac.uk/~reinhard/papers/eg2010_tania.pdf|publisher=Eurographics, State of the Art|accessdate=2 January 2014|coauthors=Cunningham, D, Reinhard, E.}}</ref> , or as inputs to algorithms for filtering and sorting the particles into groups of similar types. In some systems, sophisticated [[pattern recognition]] techniques<ref name="Rosenfeld1981">{{cite journal|last1=Rosenfeld|first1=A.|title=Image pattern recognition|journal=Proceedings of the IEEE|volume=69|issue=5|year=1981|pages=596–605|issn=0018-9219|doi=10.1109/PROC.1981.12027}}</ref><ref>{{cite book|last=Young|first=T. Y.|title=Handbook of Pattern Recognition and Image Processing|year=1986|publisher=Academic Press|isbn=0127745602}}</ref> may also be employed in order to separate different particle types contained in a heterogeneous sample.

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Static image acquisition is the most common form. Almost all microscopes can be easily adapted to accept a digital camera via a [[C mount]] adaptor. This type of set-up is often referred to as a [[digital microscope]], although many systems using that name are used only for displaying an image on a [[Video monitor#video display|monitor]].

The sample is prepared on a microscope slide which is placed on the [[Optical microscope#Stage|microscope stage]]. Once the sample has been focused on, then an image can be acquired and displayed on the monitor. If it is a [[digital camera]] or a [[frame grabber]] is present, the image can now be saved in digital format, and image processing algorithms can be used to isolate particles in the field of view and measure them.<ref>{{cite book|last=Russ|first=J.C.|title=Computer-Assisted Microscopy: The Measurement and Analysis of Images|year=1990|publisher=Springer US|isbn=978-1-4612-7868-9}}</ref> <ref>{{cite book|last=Shorte|first=S.L. (ed.)|title=Imaging Cellular an Molecular Biological Functions|year=2007|publisher=Springer|isbn=978-3-540-71330-2|pages=3-433–43|coauthors=Frischknecht, F. (ed.)|chapter=1.) Entering the Portal: Understanding the Digital Image Recorded Through a Microscope}}</ref>

In static image acquisition only one field of view image is captured at a time. If the user wishes to image other portions of the same sample on the slide, they can use the X-Y positioning hardware (typically composed of two [[linear stage|linear stages]] on the microscope to move to a different area of the slide. Care must be taken to insure that two images do not overlap so as not to count and measure the same particles more than once.