how can I set an image id?

On the product info page, I want to give the main image an id so I can do a javascript image swap from the additional images.
I'm looking in includes/templates/mytemplate/templates/tpl_modules_main_product_image.php
which is where the code for the main image is put together and it currently reads

zen_image($products_image_medium, addslashes($products_name), MEDIUM_IMAGE_WIDTH, MEDIUM_IMAGE_HEIGHT)

I have tried a variety of adding id="mainimage but to no avail.

Please help...

davidinho:

On the product info page, I want to give the main image an id so I can do a javascript image swap from the additional images.
I'm looking in includes/templates/mytemplate/templates/tpl_modules_main_product_image.php
which is where the code for the main image is put together and it currently reads

zen_image($products_image_medium, addslashes($products_name), MEDIUM_IMAGE_WIDTH, MEDIUM_IMAGE_HEIGHT)

I have tried a variety of adding id="mainimage but to no avail.

Please help...> zen_image($products_image_medium, addslashes($products_name), MEDIUM_IMAGE_WIDTH, MEDIUM_IMAGE_HEIGHT, 'id="mainimage"')should do it, i.e. adding the id assignment as 5th parameter enclosed by single quotes.

Thank you Kuroi
I was having the problem because I'd taken out the height and width so it was going in as the third param.