Considering it as an 16-bit image. The primary image is stored in the most significant byte, while the secondary image is stored in the least significant byte.
Decomposing the image :
imdata = imread('image.png');
Converting RGB 3-D Array to a Vector and typecasting to unit8 (in case the hidden image is stored in the 8 LSBs ).
pixelVals = imData(:);
pixelValsConv = typecast(pixelVals, 'uint8');
Separating both the images:
% This generates a 2D array with first column denoting the most significant digit and the second column
% denoting least significant digit.
pixelValsConv = reshape(pixelValsConv, 2, [])';
imDataPrimary = reshape(pixelValsConv(:, imOrder(1)), size(imData));
imDataSecondary = reshape(pixelValsConv(:, imOrder(2)), size(imData));
Displaying both the images:
figure;imshow(imDataPrimary);
figure;imshow(imDataSecondary);
