Hello everyone,
I'm researching leaf veination architecture, specifically leaf vein density (LVD), where I need to be able to take high resolution photos of leaves. An article posted by one of the leading authors in this field wrote a paper (Price, et al. 2014) illustrating that because your software's analysis (be it LeafGUI or ImageJ or whatever you choose) will improve with increasing photo resolution there should be a minimum requirement that needs to be met for your data to be accurate enough. They provide a formula to calculate this minimum requirement stating that,
"When a digital camera is employed to acquire images, the image size must be sufficiently large such that there are at least two pixels in the image spanning a distance equal to the magnified resolving power of the microscope."
The formula they propose is 2/(Mdmin)
Where
M=magnification
dmin=resolving power=λ0/NA
Where
λ0= mean wavelenth of light (assumed to be 0.53 um for white light)
NA=numerical aperature of the objective lens
My question is; is this formula translatable to a non-microscope imager such as a scanner or a DSLR camera?
Thank you for your time,
Victoria K.
Hi Victoria,
You should find the answers to all your questions in Sack et al. 2014 Plant Phys. LVD is NOT scale dependent as Price et al suggest (their results are due to artifacts from theLeafGUI software which gives highly inaccurate results; this is explained in depth by Sack et al 2014). You need high enough resolution to actually see all the veins (to measure minor VLA you will need microscope images). For major veins, scanner is fine (for most species). In all cases your leaves have to be chemically cleared. There is a protocol online in Prometheus that explains how to clear leaves, and images veins. (Quantifying leaf vein traits, by Scoffoni&Sack; an updated version of this with more detail should come out soon on the wiki). We use ImageJ to trace/measure VLA.
Best,
Christine
Article Leaf Vein Length per Unit Area Is Not Intrinsically Dependen...
Not sure whether the following papers could be relevant (in terms of vein enhancement/detection):
R. Su, C. Sun, C. Zhang, and T. D. Pham, A New Method for Linear Feature and Junction Enhancement in 2D Images based on Morphological Operation, Oriented Anisotropic Gaussian Function and Hessian Information, Pattern Recognition, 47(10):3193-3208, October 2014. http://dx.doi.org/10.1016/j.patcog.2014.04.024
C. Sun and P. Vallotton, Fast Linear Feature Detection Using Multiple Directional Non-Maximum Suppression, Journal of Microscopy, 234(2):147-157, May 2009. http://dx.doi.org/10.1111/j.1365-2818.2009.03156.x
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