Dear Sir, How to combine an image level's

Dear Sir,

I worked on a code that slicing the image into it 8 bit levels as in the attached link, now I want to combine the image after I worked on one of the levels of the image.

the attached link is: https://www.mathworks.com/matlabcentral/answers/77323-gray-image-to-8-bit-planes-using-bit-plane-slicing

thank you for your time