如果图像文件不存在，我想在特定文件夹中获取默认图像
所以http://xyz.de/projekt/thumb/12_2323.jpg应检查http://xyz.de/somehidden/folderonwebspace/project/thumb/12_2323.jpg是否存在。 如果不是http://xyz.de/somehidden/folderonwebspace/project/thumb/default.png
RewriteRule ^projekt/thumb/([a-zA-Z0-9_]+\.(gif|jpg|jpeg|png){1}) /somehidden/folderonwebspace/project/thumb/$1 [L]
RewriteCond %{REQUEST_FILENAME} !-f
RewriteCond %{REQUEST_FILENAME} !-d
RewriteRule .*$ /somehidden/folderonwebspace/project/thumb/default.png [L]