If condition help

[Wilfred1]

I have an img being used in a template and I am trying to create an if statement to display a defined image if one doesn't exist. Currently if an image doesn't exist the img alt is displayed. I want to be able to display a preset image if one doesn't exist instead of the alt text.

What I need is the condition part of the if statement if anyone can help me on the following:

    <if condition=???????>
        <img src="$vboptions[bburl]/quiz.php?quizid=$quiz[quizid]&image=1" alt="$quiz[title]" hspace="10" />
    <else />
        <img src="../forum/images/no_image.jpg" hspace="10" />
    </if>