Hi. I assume you're images are grayscale. How about you try this:
upperlim = 200; % define the maximum intensity
lowerlim = 100; % define the minimum intensity
A1 = double(imread('')); %read first image
B2 = double(imread('')); %read second image
m = (255-0)/(upperlim-lowerlim); % define the slope of the transfer function
b = 0 - (m*lowerlim); % define the y-intercept of transfer function
B1 = (m*A1)+b; % new image B2 = (m*A2)+b; % new image
You can play with upper and lower limits to find the ideal version of your images.
Sina
