How to get .IMG image pixels in 0 to 255 range

Question

I am working with JSRT images on MATLAB. I read the image with >IMG extension using the following code:

fid = fopen('G:\JSRTImages\JSRT001.IMG','r','b');
oneSlice = fread(fid, [2048 2048], '*uint16','b');
img = mat2gray(oneSlice, [0,4096]);
imshow(img);

The image is displayed. But when I click on any of the pixels, insted of seeing the gray level in the range of 0 to 255 I am shown 'Index' and RGB. RGB is in 0 to 1 range.

I want the image to be in 0 to 255 range for my program. Please help me in doing it.