Binary Image Subtraction

I am subtracting one binary image away from another image. But the results seem to be the inverted answer. Bascially in hex 17D8 - 0A5A = D7E but the answer Matlab writes out is FFFFFFFFFFFFF282

This is the same decimal answer except it is negative instead of positive, so: 3454 = D7E & -3454 = FFFFFFFFFFFFF282

Is there some sort of overload? and how do I overcome this problem? As it affects any other image processing I need to preform.

[FileName, PathName] = uigetfile({'*.jpg;*.tif;*.png;*.gif;*.bin','All Image Files';...
        '*.*','All Files' },'mytitle');
    Full = fullfile(PathName, FileName)
    fid = fopen(Full);
samevals = fread(fid, [2048, 2048], 'uint16');
fclose(fid);%load binary
X = samevals;
[FileName2, PathName2] = uigetfile({'*.jpg;*.tif;*.png;*.gif;*.bin','All Image Files';...
        '*.*','All Files' },'mytitle');
    Full = fullfile(PathName2, FileName2)
    fid2 = fopen(Full);
new = fread(fid2, [2048, 2048], 'uint16');
fclose(fid2);%load binary
frametempt=double(X) - double(new);

[Walter Roberson]

The most obvious possibility would seem to be that you are not subtracting in the order that you think you are.

[Colm]

I am subtracting in the right order, because I have tried it in the other (wrong) order. At the minute I am getting the right numbers but matlab seems to be putting a negative sign in hex in front of some values.

I'm taking an offset from an image with offset and signal so I should just have signal left, that's how I know what order to subtract in. Thanks though.