Averaging in a loop to stop uint16 from saturating

Hi guys, I am doing some image processing, and what happens is I record a number of images,store them in a set and do some processing and then average for a number of sets recorded.However I have a problem where because the images are uint16 it saturates before imaging, I am just wondering if there is a way to average as I go along or any other way round this. Ive tried to change the type to a larger uint but that doesnt seem to work.

if true
  for n=1:10
  stem='E:\29th April New\NEW Gain=99_No Delay_ Gate=0.02_0';
  r=n-1;
  r=int2str(r);
  combinedStr=strcat(stem,r);
  Images=99;
  t=10;
  AvgImg = uint16(zeros(1024,1280));
  for i=t:Images
      B=readimx(fullfile(combinedStr,['B000',int2str(i),'.im7']));
      C=B.Frames{1}.Components{1};
      V = C.Planes;
      Img = V{1,1};
      J = imrotate(Img,-90);
      I2 =(flip(J,2));
      FUNC=@(x)max(x(:));
      I3=medfilt2(I2,[1 1]);
      AvgImg = AvgImg +I3;
  end

    AverageImg = AvgImg/(Images-t);

    AverageImgB=90;
    AverageImgLII=(AverageImg-AverageImgB);
    K=imagesc(flipud(AverageImgLII));
  end

Answer 1

[Image Analyst]

It needs to be double to avoid clipping

AvgImg = zeros(1024,1280); % Before the loop

AvgImg = AvgImg + double(I3); % In the loop

[Robert Roy]

That seems like it helps but now my colorscale seems to be off especially with the background of the image.

[Image Analyst]

You can send in different values to caxis(). Or you can use [] if it's a gray scale image

imshow(AvgImg, []);
colormap(gray(256));
colorbar;