% SHOWLOGFFT - Displays log amplitude spectrum of an fft.%% Usage:  showlogfft(ft, figNo)%% Arguments:  ft    - Fourier transform to be displayed%             figNo - Optional figure number to display image in.%% The fft is quadrant shifted to place zero frequency at the centre and the% log of the amplitude displayed (to compress grey values).  An offset of 1% is added to avoid log(0)%% If figNo is omitted a new figure window is created.  If figNo is supplied,% and the figure exists, the existing window is reused to display the image,% otherwise a new window is created.% Copyright (c) 1999 Peter Kovesi% School of Computer Science & Software Engineering% The University of Western Australia% http://www.csse.uwa.edu.au/% % Permission is hereby granted, free of charge, to any person obtaining a copy% of this software and associated documentation files (the "Software"), to deal% in the Software without restriction, subject to the following conditions:% % The above copyright notice and this permission notice shall be included in % all copies or substantial portions of the Software.%% The Software is provided "as is", without warranty of any kind.% October 1999% September 2008 Octave compatiblefunction showlogfft(im, figNo)    Octave = exist('OCTAVE_VERSION') ~= 0;  % Are we running under Octave?         Title = inputname(1);      % Get variable name of image data                if nargin == 2	figure(figNo);         % Reuse or create a figure window with this number    else	figNo = figure;        % Create new figure window    end    imagesc(log(fftshift(abs(im))+1));    colormap(gray); title(Title), axis('image')    if ~Octave; truesize(figNo) end