# gregfreeman/matlabPyrTools

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 % MTX = steer2HarmMtx(HARMONICS, ANGLES, REL_PHASES) % % Compute a steering matrix (maps a directional basis set onto the % angular Fourier harmonics). HARMONICS is a vector specifying the % angular harmonics contained in the steerable basis/filters. ANGLES % (optional) is a vector specifying the angular position of each filter. % REL_PHASES (optional, default = 'even') specifies whether the harmonics % are cosine or sine phase aligned about those positions. % The result matrix is suitable for passing to the function STEER. % Eero Simoncelli, 7/96. function mtx = steer2HarmMtx(harmonics, angles, evenorodd) %%================================================================= %%% Optional Parameters: if (exist('evenorodd') ~= 1) evenorodd = 'even'; end % Make HARMONICS a row vector harmonics = harmonics(:)'; numh = 2*size(harmonics,2) - any(harmonics == 0); if (exist('angles') ~= 1) angles = pi * [0:numh-1]'/numh; else angles = angles(:); end %%================================================================= if isstr(evenorodd) if strcmp(evenorodd,'even') evenorodd = 0; elseif strcmp(evenorodd,'odd') evenorodd = 1; else error('EVEN_OR_ODD should be the string EVEN or ODD'); end end %% Compute inverse matrix, which maps Fourier components onto %% steerable basis. imtx = zeros(size(angles,1),numh); col = 1; for h=harmonics args = h*angles; if (h == 0) imtx(:,col) = ones(size(angles)); col = col+1; elseif evenorodd imtx(:,col) = sin(args); imtx(:,col+1) = -cos(args); col = col+2; else imtx(:,col) = cos(args); imtx(:,col+1) = sin(args); col = col+2; end end r = rank(imtx); if (( r ~= numh ) & ( r ~= size(angles,1) )) fprintf(2,'WARNING: matrix is not full rank'); end mtx = pinv(imtx);