How to replace missed files using mod_rewrite.
Here my mod_rewrite rule to check and replace missed image with NotAv.jpg icon.
#Start rewrite Engine
RewriteEngine on
#if /var/www/ “Requested file name” is not equal to (f)inded
RewriteCond /var/www%{REQUEST_FILENAME} !-f
#then rewrite all file in /public not finded with NotAv.jpg image
RewriteRule ^/public/.*$ /public/images/NotAv.jpg [PT]
#Log directives.
RewriteLog rewrite.log
RewriteLogLevel 1