Posted by
Cammer, Michael on
Oct 05, 2010; 12:21pm
URL: http://imagej.273.s1.nabble.com/Problems-calculating-proportion-green-from-pictures-tp3686725p3686726.html
This misses the very bright plant in the upper right, but selects for a color range.
run("Smooth");
run("HSB Stack");
setAutoThreshold("Default");
//run("Threshold...");
run("Spectrum");
setThreshold(47, 68);
run("Convert to Mask", " ");
run("Histogram", "slice");
result:
255 53387
_________________________________________
Michael Cammer, Assistant Research Scientist
Skirball Institute of Biomolecular Medicine
Lab: (212) 263-3208 Cell: (914) 309-3270
________________________________________
From: ImageJ Interest Group [
[hidden email]] On Behalf Of sarah Al-beidh [
[hidden email]]
Sent: Tuesday, October 05, 2010 6:40 AM
To:
[hidden email]
Subject: Problems calculating 'proportion green' from pictures
Hello all,
I am new to the list and to Image J and would be really grateful if one of you could offer some advice / assistance.
For a few months now, I have been trying to work out how to measure the vegetation cover from aerial photographs of 3m x3m plots (see attached photo for example). What I would like is a means of estimating the proportion of vegetation in each of my photographs wihtout having to draw lines around each green patch.
I have located a pdf on the Image J website describing how to determine the photosynthetic portion of a variegated leaf; however, this method (involving converting the image to greyscale and then binary) does not work for my photographs as the background here (bare soil) is not white and therefore this is not excluded when converting the image to black and white.
If anyone can give me a bit of help / direction regarding 1) whether this is possible with Image J and 2) how I could go about doing this with my photos, it would be greatly appreciated.
Many thanks in advance,
Sarah
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