Make images appear bigger in axis in guide

As you can see images appear too small I want to make them bigger how??

Here is the code

for m = 1:numOfReturnedImages
  img_name = sortedImgs(m);
  img_name = int2str(img_name);
  str_name = strcat('images\' ,img_name, '.jpg');
  returnedImage = imread(str_name);
  subplot(6, 2, m+1);
  imshow(returnedImage, []);    
end