Photoshop :: Calculate And Apply Residual Images

I would like to use Photoshop to create accurate residual images (image describing the difference between two images) and to apply such residual images to restore one of the images used to create the residual.
 
given two 8bit images (pixel values in the range [0, 255]) a residual image would be created by subtracting one image from the other:
 
Residual = Image A - Image B
 
as the potential range of this residual is [-255, 255] it must be mapped to [0, 255] to be saved as image:
 
Residual = (Image A - Image B) / 2 + 127
 
given the residual image and image B, image A can then be restored as
 
Image A = Image B + (Residual - 127) * 2 
 
so my question is: are these two processes (creating a residual image and restoring image A) possible using blending modes, and if not, can i program it somehow? I already tried it using Pixel Bender, but the Pixel Bender Photoshop plugin doesn't seem to work for pixel bender kernels that take two input images.