Authors:	Bob Dougherty (rpd@optinav.com)  Orderd by by Bill Mohler.
Installation:	Download Helmholtz_Analysis.class to the Plugins folder and restart ImageJ. Source: Helmholtz_Analysis.java
Description:	ImageJ plugin to estimate the wavelength distribution of an image with periodic features, as well as the orientation of the structures. The 2D Helmholtz equation is applied to estimate the wavenumber, k = 2*pi/lambda. Developed as a Custom ImageJ Plugin for Bill Mohler for application to images of muscle tissue. The original name of the plugin was Muscle Tone. See also helmholtz.pdf.
Reference:	"Measurement of muscle disease by quantitative second-harmonic generation imaging," S.V Plotnikov, A.M. Kenny, S.J. Walsh, B. Zubrowski, C. Joseph, V.L. Scranton, V.A. Kuchel., D. Dauser, M. Xu, C.C. Pilbeam, D.J. Adams, R.P. Dougherty, P.J. Campagnola and W.A. Mohler, J. Biomed. Opt., 2008, Jul-Aug;13(4):044018.
Sample:	Input image Dialog Output Average output
History:	August 2005: First version of Muscle Tone October 11, 2011: Renamed Helmholtz Analysis and posted. Version 1. October 12, 2011. Fixed a bug that caused incorrect averages and sometimes array index out of bounds crashes for non-square images. Version 2. October 15, 2011. Hardwired choices for filtering radii and averaging tolerances. Added checkboxes to select outputs. Added support for ROIs. Added progress bar for averaging. Improved handling on invalid points. Weighted average for phi.
License:	Copyright (c) 2005, 2011 OptiNav, Inc. All rights reserved. Redistribution and use in source and binary forms, with or without modification, are permitted provided that the following conditions are met: Redistributions of source code must retain the above copyright notice, this list of conditions and the following disclaimer. Redistributions in binary form must reproduce the above copyright notice, this list of conditions and the following disclaimer in the documentation and/or other materials provided with the distribution. Neither the name of OptiNav, Inc. nor the names of its contributors may be used to endorse or promote products derived from this software without specific prior written permission. THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
ImageJ:	ImageJ can be freely downloaded from the ImageJ web site.