matlab 判断是否存在某文件夹，若不存在，新建一个文件夹

1. 判断是否存在指定的video_name, 若不存在，则在给定save_path下，新建一个video_name文件夹：

1   sec_path = [save_path, video_name, ‘/‘];
2   if ~exist(sec_path,‘file‘)
3      mkdir([save_path, video_name]);
4   end

2. 将gpuArray转换为matlab可以保存的格式，如：uint8 等。
   if you save the gpuArray data directly, it will warning you some errors like this:


and translate it into numeric or logical is necessary...

    % gpuArray to matlab format, person_image is the gpuArray and first translate it into 
      single format using "gather" function which is the matlab inside function.

    person_image = im2uint8(gather(person_image));