MATLAB把pgm格式转换为jpg

最近下载了YaleB人脸数据库，所有图片都是.pgm格式的。在MATLAB上将所有.pgm格式的图片转为jpg。例程如下：

% addpath(genpath(pwd))
path = '/Users/yuyang/Documents/MATLAB/Yale/CroppedYale';
Folder = dir(fullfile(path));%CroppedYale下的每个文件夹
numfolder = length(Folder);
outfolder = 'Yale_jpg';mkdir(outfolder);
outpath = ['/Users/yuyang/Documents/MATLAB/Yale/',outfolder,'/'];
for n = 1:numfolder
    fname = Folder(n).name;
    mkdir(outpath,fname);
    imlist = dir(fullfile([path,'/',fname,'/','*.pgm']));
    m =