%'interp2_uvmat': linearly interpolate an image or scalar defined on a %regular grid USE Matlab interp2 instead %-------------------------------------------------------------------- %OUTPUT: % A_out: matrix of interpolated values at positions (XIMA,YIMA) % %INPUT: % A matrix (npy,npx) to interpolate %XIMA: matrix of non-integer x index values (npY,npX) %YIMA: matrix of non-integer y index values (npY,npX), (with the same size as XIMA) %======================================================================= % Copyright 2008-2024, LEGI UMR 5519 / CNRS UGA G-INP, Grenoble, France % http://www.legi.grenoble-inp.fr % Joel.Sommeria - Joel.Sommeria (A) univ-grenoble-alpes.fr % % This file is part of the toolbox UVMAT. % % UVMAT 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. % % UVMAT 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 (see LICENSE.txt) for more details. %======================================================================= function A_out=interp2_uvmat(A,XIMA,YIMA) npx=size(A,2); npy=size(A,1); npX=size(XIMA,2); npY=size(XIMA,1); XIMA=reshape(XIMA,1,npX*npY)+0.5;%indices corresponding to XIMA, reshaped in a matlab vector YIMA=reshape(YIMA,1,npX*npY)+0.5;%indices corresponding to XIMA, reshaped in a matlab vector X_delta=XIMA-floor(XIMA);%distance to the closest integer value XIMA=floor(XIMA);%integer x index on the image Y_delta=YIMA-floor(YIMA);%distance to the closest integer value YIMA=floor(YIMA);%integer x index on the image flagin=(XIMA>=1 & XIMA<=npx-1 & YIMA >=1 & YIMA<=npy-1);%flagin=1 inside the original image ind_in=find(flagin);%list of indices of XIndex for valid values of image indices (inside the original image) ind_out=find(~flagin); vec_A=double(reshape(A(:,:,1),1,npx*npy));%reshape the original image as a Matlab image vector ICOMB=((XIMA-1)*npy+(npy+1-YIMA));%determine the indices in the image Matlab vector corresponding to XIMA and YIMA ICOMB=ICOMB(flagin);%selection of the valid indices X_delta=X_delta(ind_in); Y_delta=Y_delta(ind_in); A_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); A_out(ind_out)=zeros(size(ind_out)); A_out=reshape(A_out,npY,npX);%interpolated image