Is it possible to create a code that will automaticallly switch a hotlinked image with another e.g no_hotlinking.gif ?

No. You need to use Apache's mod_rewrite for this.

could you then perhaps use this idea, of screening an image with a transparent image so the transparency is linked/saved instead, but use the transparency to cover your entire page at a given resolution with the same effect?
Ofcourse you would need to make sure the transparency was the topmost layer of every page somehow aswell.

<DIV STYLE="background-image:url(''); background-repeat:no-repeat; padding:0px; margin:0px; width:276; height:110;">
<IMG SRC="" WIDTH="276" HEIGHT="110"  BORDER="0">
commented: Good idea, it would certainly stop people directly saving your images easily. +1

You also can't stop someone probing your code to find the image link; and if they're inclined to hotlink your images; they'll probably be even more inclined to do so if they encounter lax security.

Good idea though...

I'd advise looking into some server side techniques. Quite alot of the things you've been asking about here with Javascript (cookies, redirection, dynamically generated content, referer detection [which is what you'll need for this]) are much better suited to server-side scripts and technologies.

ROFL! Give that Guy a Cigar! Well spotted! yes just an example, I wondered if anyone would pick up on that :P :D (ps if a mod could edit out that image example to save poor old googles bandwidth please do! seems my edit time is up for that post)

Reason Things I ask for doing require mainly client side is because my site is free hosted and I dont have access to the server.
Perhaps this could be gotten around. If I could ftp upload to a remote server could I use a remote example of Apache's mod_rewrite ?
I suppose the images I want to pretect would also have to be hosted on that server.....hmmm...nix that !
I thought my idea might foil the casual ripper though, maybe along with a meta tag to remove the ie image toolbar?
Be much better imo to disble right click menu's 'veiw source' somehow, and remove the browsers veiw source. ?? Probably still wouldnt stop some.
Any ideas for a client side javascript or remote php that could auto add a transparent watermark to any attached or uploaded image?

You only need FTP access to write .htaccess files that can contain ModRewrite directives.... But they'll only work on an Apache server. Free hosting even on Apache might have all overrides disabled; which would prevent you using anything in .htaccess files.

You could probably implement an image protector using PHP... you have the same access to the server environment variables (which would let you detect who or what is accessing your images); but you'd have to do something messy like print images to the outputstream as binary data for a real protection. I did something like that a while back in Perl, it was for uploaded image validation rather than hotlink protection, but it used that principle..

You can't disable the view source button >_< Only a browser deliberately programmed with "invoke any annoying directive a web page asks me to" functionality would support that.

There are PHP image manipulation functions built into PHP.. For watermarking:

Take the basic image manipulation parts from here:

And combine them with the loadimagefromjpg function used here: