UNIX for Dummies Questions & Answers

I am running apache web server on CentOS5.2
I have the directory in which stores a lot of images.(/var/www/html/images)
I want to deny everyone from directly accessing the directory but still allow images in the directory to be used by HTML (/var/www/html/pic.html <img src="https://www.unix.com/images/hotimg.jpg">)

=>someone cannot access that specific directory directly.
1)create .htaccess in images directory
2)type following lines and save
order allow,deny
deny from all

but I don't know how to allow images in the directory to be used by HTML(pic.html <img src="https://www.unix.com/images/hotimg.jpg">)

thanks in advance

Example .htaccess

Code:

SetEnvIfNoCase Referer "^http://$" html_ref=1
Order Allow,Deny
Allow from env=html_ref

Will allow access only if the browser submits a referer field starting with "http://" (e.g. embedded in a site)

Life Saver~
It works perfectly
I will learn mod_setenvif

Code:

SetEnvIfNoCase Referer "^http://domainname/pic.html$" html_ref=1
Order Allow,Deny
Allow from env=html_ref

Thank you very much~