Why are we asking you to enter the text from an image?
We have problems with spammers. (Who doesn't!)
Automated computer programs find contact forms like ours, and then use them to send spam.
A rogue program can use a contact form as a veritable post office, sending out thousands of messages without any possibility of being tracked back to the source.
We use randomly generated images like this for security. A spammer would need a lot of time and resources to "read" the code automatically. Theoretically he could use OCR (Optical Character Recognition) to read it without human intervention. But we overlay the text with interfering graphics that can defeat most OCR programs.
One problem: the graphical obfuscation makes it harder for you to interpret the characters. That's why we offer a button to generate a new code if the one you see is illegible.
Bottom line: By entering the code you see, you're helping our server confirm that you're a real human being and not an automated computer program -- and you're helping frustrate those who would spam all of us.