using mod_rewrite to change url path

You can achieve that with mod_rewrite putting something like this in the .htaccess file of your root folder:

RewriteEngine on

# the first condition is for avoiding an infinite loop
RewriteCond %{REQUEST_URI} !^/test/.*
RewriteRule ^(.*)$  /test/$1

This will redirect to /test/ all the pages/files requested from /.

If you only want to redirect some files use more specific rule(s):

RewriteEngine on

# the condition is for avoiding an infinite loop
RewriteCond %{REQUEST_URI} !^/test/.*
# redirecting only images files and files that start with "doc"
RewriteRule ^(.*\.(jpg|png|gif))$  test/$1 [L]
RewriteRule ^(doc.*)$  test/$1 [L]

Or if you want to use different folders:

RewriteEngine on

# the condition is for avoiding an infinite loop
RewriteCond %{REQUEST_URI} !^/images/.*
RewriteCond %{REQUEST_URI} !^/docs/.*
# redirecting only images files and files that start with "doc"
RewriteRule ^(.*\.(jpg|png|gif))$  images/$1 [L]
RewriteRule ^(doc.*)$  docs/$1 [L]