Creating a form verification image / captcha using ASP and csImageFile
This demo shows how to create an image of some text in a web form and then compare user input to check if they entered the text correctly. This technique is frequently used to reduce the amount of unwanted form submisions caused when automated programmes fill in online forms. By using csImageFile to generate the image it is easy to modify the colours, font and size of the image to match the web page where it is used.
You can try the example by entering the code in the box and submitting the form.
The example code can be downloaded but you must also have the trial csImageFile component installed for it to run. It uses classic ASP. Here are the files.