# source:trunk/src/interp2_uvmat.m@1093

Last change on this file since 1093 was 1093, checked in by g7moreau, 3 years ago
File size: 2.6 KB
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1%'interp2_uvmat': linearly interpolate an image or scalar defined on a
2%regular grid        USE Matlab interp2 instead
3%--------------------------------------------------------------------
4%OUTPUT:
5% A_out: matrix of interpolated values at positions (XIMA,YIMA)
6%
7%INPUT:
8% A matrix (npy,npx) to interpolate
9%XIMA: matrix of non-integer x index values (npY,npX)
10%YIMA: matrix of non-integer y index values (npY,npX), (with the same size as XIMA)
11
12%=======================================================================
13% Copyright 2008-2021, LEGI UMR 5519 / CNRS UGA G-INP, Grenoble, France
14%   http://www.legi.grenoble-inp.fr
15%   Joel.Sommeria - Joel.Sommeria (A) legi.cnrs.fr
16%
17%     This file is part of the toolbox UVMAT.
18%
19%     UVMAT is free software; you can redistribute it and/or modify
20%     it under the terms of the GNU General Public License as published
21%     by the Free Software Foundation; either version 2 of the license,
22%     or (at your option) any later version.
23%
24%     UVMAT is distributed in the hope that it will be useful,
25%     but WITHOUT ANY WARRANTY; without even the implied warranty of
26%     MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
28%=======================================================================
29
30function A_out=interp2_uvmat(A,XIMA,YIMA)
31npx=size(A,2);
32npy=size(A,1);
33npX=size(XIMA,2);
34npY=size(XIMA,1);
35XIMA=reshape(XIMA,1,npX*npY)+0.5;%indices corresponding to XIMA, reshaped in a matlab vector
36YIMA=reshape(YIMA,1,npX*npY)+0.5;%indices corresponding to XIMA, reshaped in a matlab vector
37X_delta=XIMA-floor(XIMA);%distance to the closest integer value
38XIMA=floor(XIMA);%integer x index on the image
39Y_delta=YIMA-floor(YIMA);%distance to the closest integer value
40YIMA=floor(YIMA);%integer x index on the image
41flagin=(XIMA>=1 & XIMA<=npx-1 & YIMA >=1 & YIMA<=npy-1);%flagin=1 inside the original image
42ind_in=find(flagin);%list of indices of XIndex for valid values of image indices (inside the original image)
43ind_out=find(~flagin);
44vec_A=double(reshape(A(:,:,1),1,npx*npy));%reshape the original image as a Matlab image vector
45ICOMB=((XIMA-1)*npy+(npy+1-YIMA));%determine the indices in the image Matlab vector corresponding to XIMA and YIMA
46ICOMB=ICOMB(flagin);%selection of the valid indices
47X_delta=X_delta(ind_in);
48Y_delta=Y_delta(ind_in);
49A_out(ind_in)=(1-Y_delta).*(1-X_delta).*vec_A(ICOMB)+Y_delta.*(1-X_delta).*vec_A(ICOMB-1)+X_delta.*(1-Y_delta).*vec_A(ICOMB+npy)+X_delta.*Y_delta.*vec_A(ICOMB+npy-1);
50A_out(ind_out)=zeros(size(ind_out));
51A_out=reshape(A_out,npY,npX);%interpolated image
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