Magento 1.4

Default Product Details image size is 265x265.

All of our product images will be probably 2x taller than wide, and even if we pad them to make them square 265 will be too small to see detail in the image, so we'd like to make the image taller.

I found the media.phtml file

How would we go about modifying this file/Magento so that the product details page image is 265W x 530H.

This looks like the code that displays the image.

<p class="product-image">
    <?php
        $_img = '<img src="'.$this->helper('catalog/image')->init($_product, 'image')->resize(265).'" alt="'.$this->htmlEscape($this->getImageLabel()).'" title="'.$this->htmlEscape($this->getImageLabel()).'" />';
        echo $_helper->productAttribute($_product, $_img, 'image');
    ?>
</p>

Thanks