RewriteEngine On
RewriteCond %{REQUEST_URI} \.(jpg|jpeg|gif|png)$ [NC]
RewriteCond %{REQUEST_FILENAME} !-f
RewriteCond %{REQUEST_FILENAME} !-d
RewriteRule .*$ /no_picture.png [L]
Let's break it down as to what each line means.
RewriteCond %{REQUEST_URI} \.(jpg|jpeg|gif|png)$ [NC]
Check to see if the requested file is of a file extension in the parentheses
(). In this case, we're testing to see if the file name ends in either
.jpg,
.jpeg,
.gif or
.png
RewriteCond %{REQUEST_FILENAME} !-f
RewriteCond %{REQUEST_FILENAME} !-d
Check that the file is not there and it's also not a directory.
RewriteRule .*$ /no_picture.png [L]
If a requested resource/file passes all those tests, then it's an image that does not exist. So serve back the image of
no_picture.png to the browser. This will keep the filename. If you want to redirect to the
no_picture.png filename, change
[L] to
[R]
