create temporary images??

I dont know if this would make sense but I would appreciate if someone gives me some info on it. I want to show an image to the user but I don't want the user to be able to save the URL of that image and view it later on. Is there any way that I could load an image into a HTML page without giving away its URL on the server?

I've also noticed that sometimes when you view the source of an image on a website it's just a link to a server-side page with a query string. For example the link to my avtar is http://www.vbforums.com/avatar.php?userid=22277&dateline=1022378610. That's just a link to a php page instead of a link to a GIF file. How does a serverside page serve an image like that?
help this idiot out please:D

Firstly rather than saving the URL and viewing it later most people will right click and save the full image locally.

You can use server-side scripts to display images according to various input parameters by creating a byte stream to the users browser and setting the content-type in the HTTP header to be whatever file type you are streaming.

Quite often when you see this done the file is stored in a database in a BLOB (Binary Large OBject) field and therefore needs to be streamed to the browser as there isn't actually a physical path to the file.

It could be possible to create a "temporary" image by passing in a date to a server-side script that checks it is within a certain timespan before streaming the image. Savvy users might spot this and be able to change the date/time passed in.

Let me know if you need to know anything else.

HTH

DJ

It's probably not feasible to prevent a determined user from acquiring the image. One thing that would help is to embed the image into a flash movie and display the movie instead of the image. Flash is pretty efficient, so the final file needn't be much larger than the original image. Trying to save a flash file from I.E., is a bit of a pain, plus it would be hard to use the image for anything else unless you got a flash decompiler.

Also, there are ways to automatically generate flash "movies" (they don't always move) on the fly by the web server. Not sure about how this might be done in a .NET environment, but do a search on Ming for Apache. If worse came to worse, you could co-exist IIS and Apache on the same server. (Ming + Apache being free, of course)

cudabean

thanks for the ideas guys. For now I'm just doing this: There is an asp page that gets an image id from the query string. I just write the image back using Response.WriteFile()... I don't know if this is the correct way but it seems to be working. Now I just need to check the refferal url and make sure they are not coming from another website. If the refferal url is from some other website then it wouldnt show the image. works fine with me :D
I think I'm ok with the users saving the images to their harddrive. I was mainly concerned about linking to my webserver (for some top-secret reason :bigyello: )

hmm now how would I go about checking the refferal url?:rolleyes:

Mr. Polite, that is the correct way, and really only way to handle that situation! The Flash idea was unique for sure, but you cannot guarantee a client has it.

The referURl is available through

VB Code:

Page.Request.UrlReferrer.PathAndQuery

Response.WriteFile() should work fine as long as the images aren't too large (I'm talking over 10Mb here) - it gets a little inefficient on the server memory.

I can supply code to break the streaming down into chunks if are are using very large files - just give me a shout if you want it.

DJ