Magento. Removing white image background

<div> <a href="<?php echo $_product->getProductUrl() ?>" title="<?php echo $this->stripTags($this->getImageLabel($_product, 'small_image'), null, true) ?>"><img src="<?php echo $this->helper('catalog/image')->init($_product, 'small_image')->constrainOnly(TRUE)->keepAspectRatio(TRUE)->keepFrame(FALSE)->resize(210); ?>" width="164" height="210" alt="<?php echo $this->stripTags($this->getImageLabel($_product, 'small_image'), null, true) ?>" /></a>