@Daeyeon Koh - I think that you are saving the figure rather than the image that is displayed in the figure to the file
saveas(gcf,fullfile(ImageData_Address00,sprintf('RabbitSimul_0.0cc_%d.jpg',i)));
and so it makes sense that the size is not what you expect it to be? I suspect if you open the image, you will see the axes, labels, and other components of the figure. Is this intentional or do you want to be saving the image Mod_SPTRGMimage{i,1} to file as
imwrite(Mod_SPTRGMimage{i,1},fullfile(ImageData_Address00,sprintf('RabbitSimul_0.0cc_%d.jpg',i)));