Conifer needle surface area minus shadows

Posted by Tree-Doc on Dec 08, 2013; 11:03pm
URL: http://imagej.273.s1.nabble.com/Conifer-needle-surface-area-minus-shadows-tp5005845.html

I have about 250 scans of conifer tree needles and need to measure their
surface area. I've been using Threshold Colour to adjust the HSB to remove
part of the shadow, but I notice that depending on the exact threshold
numbers I use, my resulting area calculation will vary by 25% or more (not
good).

Is there a better way to do this to achieve more accurate results?

My methods: Adjust HSB to remove as much of the shadow as I can without
removing green needle.
Converting to binary.
Despeckling the noise.
Process>Binary>Close to capture the white center streaks in the needles.
Filling the Holes.
And analyzing particles

Here is an example of the images I'm working with. I know the scans aren't
ideal, but capturing better images in not an option.