Re: Quantification of axon Twist

Posted by Herbie on Mar 24, 2017; 1:14pm
URL: http://imagej.273.s1.nabble.com/Quantification-of-axon-Twist-tp5018355p5018363.html

Dear Eric,
dear list,

there were two related errors in my previous posts.

1.
The orientation angle changes _counter_ clockwise.

2.
Consequently my interpretation

"With your image, it is interesting that the 90deg bending of the axons
shows up nicely [...]"

is wrong!
_________________________________________

re 2.

It turns out that the plateau between 25deg and 90deg is caused by a
very low frequency modulation in the image. It can best be seen in the
power spectrum. Maybe it is an illumination artifact.

Using a high-pass filter to remove the low frequency component leads to
the attached result which appears sound. (The local maximum at 90deg is
due to the grid-like shadow in the image.)

Best

Herbie

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