i got error when i using imwrite function

When i run the following code error occured:

Error using imwrite (line 442)

Cannot write signed integer data to a JPEG file.

Error in cnn (line 19)

imwrite( data1, outfile, 'jpg');

data1 is the 512x512 int16.

clc;
clear all;
close all;
dirpath='C:\Users\suraj\Desktop\Tumor\New folder\brainTumorDataPublic_1-766\';
dirpath1='D:\Thesis Work\Thesis Report\jpgdataset\';
type='mat';
type1='jpg';
oldvar = '';
for j=4:9
    infile = fullfile(dirpath, sprintf('%d.mat', j));
    outfile = fullfile(dirpath1, sprintf('HK%d.jpg', j));
    datastruct = load(infile);
    fn = fieldnames(datastruct);
    firstvar = fn{1};
    data = datastruct.(firstvar);
    data1 = data.image;
    
    imwrite( data1, outfile);
    if ~strcmp(oldvar, firstvar)
      fprintf('loading from variable %s as of file %d\n', firstvar);
    end
end