useful functions for simulations, created by ESRF people mainly (free to use)

[CreaPhase.git] / utilities_ESRF / cut.m

diff --git a/utilities_ESRF/cut.m b/utilities_ESRF/cut.m
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+## Copyright (C) 2012 P. Cloetens
+## 
+## This program is free software; you can redistribute it and/or modify
+## it under the terms of the GNU General Public License as published by
+## the Free Software Foundation; either version 2 of the License, or
+## (at your option) any later version.
+## 
+## This program is distributed in the hope that it will be useful,
+## but WITHOUT ANY WARRANTY; without even the implied warranty of
+## MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+## GNU General Public License for more details.
+## 
+## You should have received a copy of the GNU General Public License
+## along with this program; if not, write to the Free Software
+## Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
+
+## cut
+## function imcut = cut(im, nn, mn[, cnn, cmn])
+##      cuts a sub-matrix out of a larger matrix
+##      cuts in the center of the original matrix, except if new center is specified
+##      NO CHECKING of validity indices sub-matrix!
+##
+##      arguments:
+##      argument 1: original matrix im
+##      argument 2: number of rows in result
+##      argument 3: number of columns in result
+##      argument 4: center row around which to cut ( default: center )
+##      argument 5: center column around which to cut ( default: center )
+##
+##      examples:
+##          im_roi = cut(im, 1024, 1024)                -> cut center 1024x1024 pixels
+##          im_roi = cut(im, 1024, 1024, 600.5, 700.5)  -> cut 1024x1024 pixels around pixels (600-601, 700-701)
+
+## Author: P. Cloetens <cloetens@esrf.eu>
+## 
+## 2012-10-14 P. Cloetens <cloetens@esrf.eu>
+## * Initial revision
+
+function imcut = cut(im, nn, mn, cnn, cmn)
+    if !exist('cnn', 'var')
+        cnn = [];
+    endif
+    if !exist('cmn', 'var')
+        cmn = [];
+    endif
+    
+       [n,m] = size(im);
+       if isempty(cnn)
+               cnn = (n+1)/2;
+       endif
+       if isempty(cmn)
+               cmn = (m+1)/2;
+       endif
+       
+       rb = round(0.5+cnn-nn/2);
+       re = nn+rb-1;
+       cb = round(0.5+cmn-mn/2);
+       ce = mn+cb-1;
+       imcut = im(rb:re, cb:ce);
+endfunction