Create a mask based on pixel values

I want to have my code be able to create a mask based on a range of pixel values. For example, if a part of the images' pixels range from 50-125, I want it to only mask that range

Answer 1

[Rik]

IM = uint8(randi(255,100,80));
L= IM >=50 & IM <=125;

[ali eskandari]

I want to substract two images and show the results in another figure. For instance, if the subtraction matrix has 0 value indicate the elements with black, if it has negative value show them with red and if it has positive value show with blue. How can I do that?

[Rik]

This is not a comment, but a question. Have a read here and here. It will greatly improve your chances of getting an answer.