Adding random numbers in dicom images using Matalb

I am modifying dicom images by replacing the actual pixel values with eight fixed numbers. Here is one line of my script (below).

image_list=dir('*.dcm');
   for i=1:40
     img=dicomread(image_list(i).name);
     imgHdr = dicominfo(image_list(i).name);
  %Bone 
  img(1:410,1:410) = 3000*uint16(img(1:410,1:410)>1590 & img(1:410,1:410)   <=3000)+uint16(img(1:410,1:410)<=1590 | img(1:410,1:410)>2000).*img(1:410,1:410);

    dicomwrite(img, ['N' num2str(i) '.dcm'], imgHdr,'CreateMode','Copy')
    end

Then, I am trying to add random numbers (between 1 and 100) to only one fixed values, i.e. 3000 (as shown in the script) so it will be between 3000 and 3100 and the other fixed numbers are still the same. I tried

img(1:410,1:410)= img(1:410,1:410) +randi([3000 3100],410,410);

but it didn't work. How can I do that ?

Any assistance would be appreciated, thanks.

TA