Multipage Tiff write in MATLAB doesn't work

Question

I'm reading in a Tiff using the below function, which works fine, but when I try to use my write function to write that same Tiff back to a different file, it's all 255's. Does anyone know how to fix this? Thanks, Alex.

function Y = tiff_read(name)
% tiff reader that works

info = imfinfo(name);
T = numel(info);

d1 = info(1).Height;
d2 = info(1).Width;

Y = zeros(d1,d2,T);
for t = 1:T
    temp = imread(name, t, 'Info',info);
    Y(:,:,t) = temp(1:end,1:end);
end

% Tiff writer that doesn't work
function tiff_write(Y,name)
% Y should be 3D, name should end in .tif
T = size(Y,3);
imwrite(Y(:,:,1),name);
for t = 2:T
    imwrite(Y(:,:,t),name,'WriteMode','append');
end

Answer 1

Try using this line :

Y = zeros(d1,d2,T,'uint16');

instead of this one:

Y = zeros(d1,d2,T);

Your data are likely in uint16 format and when you export you clip the maximum value to 255 (uint8), which makes pixel with values greater than 255 (a LOT of them if your data is in uint16) appear white.

Otherwise you might want to use this line:

function tiff_write(Y,name)
   % Y should be 3D, name should end in .tif
   for t = 2:T
     imwrite(Y(:,:,t)/255,name,'WriteMode','append');
   end