Re: Generating random points and tallying proportion of points that fall within object
Posted by
Anderson, Charles (DNR) on
Jun 03, 2014; 4:19pm
URL: http://imagej.273.s1.nabble.com/Generating-random-points-and-tallying-proportion-of-points-that-fall-within-object-tp5007988p5008003.html
Do some preliminary measurements to identify approximately the radius of the largest vessel likely to be encountered for each species. Record a buffer width larger than this radius for future use.
Do the thresholding and create a mask. Run analyze particles, including particles on the edge, recording centroids as well as areas. Use the total vessel area and the image area to calculate proportion of image area occupied. In post-processing with a stats program or spreadsheet, delete those records whose centroid falls within the buffer width of the edge of the image. The remaining particles give the size distribution of complete particles. The count of remaining particles and the area of the central region (image area - buffered area) allow an estimate of vessels / unit area.
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From: ImageJ Interest Group [mailto:
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Sent: Monday, June 02, 2014 5:36 PM
To:
[hidden email]
Subject: Re: Generating random points and tallying proportion of points that fall within object
I guess I omitted some important information on what I am trying to do. The actual estimate of the size, counts, and proportion of image area occupied by the objects of interest will likely be biased because some of the objects of interest (vessels) are only partially included within the image. I am working with images of cross sections of wood for different species. The nature of the distribution of the vessels within an image varies depending on species, however, many of the images have vessels only partially within the image. Including or excluding these partial vessels in the actual estimates is likely to introduce bias among species that vary in their vessel sizes. Do you have any other suggestion on how I should deal with this bias due to partial vessels in the images apart from my method (random generation of points and tallying the proportion of points that fall within vessels)?
Thanks.
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