PhpThumb需要大量的磁盘空间

我正在使用phpthumb: http://phpthumb.sourceforge.net/

我的服务器上有大约500Mb的图像，phpthumb为每个图像创建2个小拇指(100x100 300x300)。问题是phpthumb文件夹(缓存图像)是7GB。这怎么可能呢?500MB的图片和7GB的拇指?

但是，如果有人知道如何解决这个问题，你能告诉我一些其他的方法来创建拇指而不使用太多的磁盘空间吗?

编辑:以下是7GB缓存文件夹中的内容:

 wonder@wonder:~/webapps/mysite/phpthumb/cache$ ls
pThumbdcgAn0  pThumbgOV4iT  pThumbk7kCaR  pThumbnjieys  pThumbPYULm9  pThumbrpmRrw  pThumbTEwQ7J  pThumbV0veyL  pThumbwQ9q6G  pThumbYerk1C  pThumbZZuYuh
pThumbdcgpYI  pThumbgOzg8d  pThumbk7kNm7  pThumbnjKVPy  pThumbPYXGiL  pThumbrpMZWp  pThumbtEXnH5  pThumbv0wl2w  pThumbWQbPOg  pThumbyeRvzX  pThumbZZV7lg
pThumbdCH7V8  pThumbgp1cEO  pThumbk7mCU9  pThumbnJlTyj  pThumbPyy54W  pThumbrPnANX  pThumbTEXtUw  pThumbv0wSQJ  pThumbWqC6Z5  pThumbYEsW3P  pThumbZZvxCD
pThumbdcHexw  pThumbgp1Whz  pThumbk7W8mB  pThumbnjmSux  pThumbpyYiD3  pThumbRpnIJb  pThumbteZZjl  pThumbv0X5R0  pThumbwqgpU1  pThumbYEUOtG  pThumbZZXaCj
pThumbdCI3vo  pThumbgp6H6n  pThumbk7wI6P  pThumbnjNjg6  pThumbpYZ4Gx  pThumbRpnO9s  pThumbTf12uv  pThumbv0XInS  pThumbwqGx7p  pThumbYEVl3E  pThumbZzXPmQ
pThumbdCLpoL  pThumbgpAuiN  pThumbk89Sgb  pThumbnjNUa9  pThumbPZ1ZgP  pThumbrpPUU8  pThumbtf8DKF  pThumbv0xrXD  pThumbWqHG77  pThumbyEW6aJ  pThumbZZyvlJ
pThumbdcmGQa  pThumbgpbD5D  pThumbk8AuZH  pThumbnJNXur  pThumbPz3s0y  pThumbrPq1iF  pThumbTF9EAZ  pThumbV0zYo9  pThumbwQhr5Z  pThumbyEWeyI  pThumbzZYwnw
pThumbdCOoaQ  pThumbgpbNws  pThumbk8E6c4  pThumbnJpfR6  pThumbpz4Ri4  pThumbrPqHbg  pThumbtfAwO2  pThumbV11Qhr  pThumbWqkIun  pThumbYEWSSb  pThumbZZZ81f
pThumbdCQzjy  pThumbgpdBn6  pThumbk8hkeR  pThumbnJpOpb  pThumbpz6LJE  pThumbrpqjno  pThumbTfCloj  pThumbv123te  pThumbWQkmfe  pThumbyeXUVM  pThumbzZz88B.....

wonder@wonder:~/webapps/mysite/phpthumb/cache$ du
4   ./0/0b/0b4/0b44
8   ./0/0b/0b4
12  ./0/0b
16  ./0
4   ./4/49/495/4958
8   ./4/49/495
12  ./4/49
4   ./4/4e/4e7/4e72
8   ./4/4e/4e7
12  ./4/4e
28  ./4
5839852 .