Image Interpolation (ba_interp2)

Fast nearest, bi-linear and bi-cubic interpolation for image data

% Fast nearest, bi-linear and bi-cubic interpolation for image data
%
% Usage:
% ------
% Z = ba_interp2(F, X, Y, [method])
%
% where method is one off nearest, linear, or cubic.
%
% F is a WxHxD Image with an arbitrary number of layers D.
% X, Y are I_1 x ... x I_n matrices with the x and y coordinates to
% interpolate.
% Z is a I_1 x ... x I_n x D matrix, which contains the interpolated image channels.
%
% Notes:
% ------
% This method handles the border by repeating the closest values to the point accessed.
% This is different from matlabs border handling.
%
% Example
% ------
%
% %% The mandrills eye
% clear
% IMG=load('mandrill');
% IMG = ind2rgb(IMG.X, IMG.map);
% [Dx Dy] = meshgrid(130:0.1:250, -150:0.1:-50);
%
% R = [cos(pi/4) sin(pi/4); -sin(pi/4) cos(pi/4)];
% RD = R * [Dx(:)'; Dy(:)'] + 250;
% RDx = reshape(RD(1,:), size(Dx));
% RDy = reshape(RD(2,:), size(Dy));
%
% methods = {'nearest', 'linear', 'cubic'};
% la=nan(1,3);
% for i=1:3
% la(i) = subplot(2,2,i);
% tic;
% IMG_R = ba_interp2(IMG, RDx, RDy, methods{i});
% elapsed=toc;
% imshow(IMG_R);
% title(sprintf('Rotation and zoom using %s interpolation took %gs', methods{i}, elapsed));
% end
% linkaxes(la);
%
% License:
% --------
% GPL
% (c) 2008 Brian Amberg
% http://www.brian-amberg.de/