He = [ 0.6500286; 0.704031; 0.2860126 ];
DAB = [ 0.26814753; 0.57031375; 0.77642715];
Res = [ 0.7110272; 0.42318153; 0.5615672 ]; % residual
% combine stain vectors to deconvolution matrix
HDABtoRGB = [He/norm(He) DAB/norm(DAB) Res/norm(Res)]';
RGBtoHDAB = inv(HDABtoRGB);