<?php
$halfPath='./media/catalog/product';
$user="username"; //username for SOAPv2 api
$pass="password"; //password for above user
$products = array(20,21,22); //array of product IDs to be converted
ini_set('display_errors',E_ALL);
error_reporting(E_ALL);
define('MAGENTO_ROOT', getcwd());
$mageFilename = MAGENTO_ROOT . '/app/Mage.php';
require_once $mageFilename;
Mage::app();
$baseurl=Mage::getBaseUrl(Mage_Core_Model_Store::URL_TYPE_WEB);
$client = new SoapClient($baseurl.'api/v2_soap/?wsdl');
	$sessionId = $client->login($user,$pass);

$mediaApi = Mage::getModel("catalog/product_attribute_media_api");
function kariobhai($jagah)
{
	global $halfPath;
$input = imagecreatefrompng($halfPath.$jagah);
        $width=imagesx($input);
        $height=imagesy($input);
        $output = imagecreatetruecolor($width, $height);
        $white = imagecolorallocate($output,  255, 255, 255);
        imagefilledrectangle($output, 0, 0, $width, $height, $white);
        imagecopy($output, $input, 0, 0, 0, 0, $width, $height);
		ob_start();
	imagejpeg($output);
	$img_content = ob_get_clean();
	imagedestroy($output);
	return base64_encode($img_content);
		}

foreach($products as $prodID){
$items = $mediaApi->items($prodID);
	foreach($items as $item) {
	if(substr($item['file'],-3)=='png'){
		$direction=kariobhai($item['file']);
		$str = preg_replace('/.*\/(.*?)\.png$/','$1', $item['file']);
		$newFile = array(
		'name'=>$str,
	'content' => $direction,
	'mime' => 'image/jpeg'
);
		$result = $client->catalogProductAttributeMediaCreate(
$sessionId,
$prodID,
array( 'file'=>$newFile,'label' => $item['label'], 'position' => $item['position'], 'types' => $item['type'], 'exclude' => $item['exclude'])
);
	if($result) $client->catalogProductAttributeMediaRemove($sessionId, $prodID, $item['file']);
    }
	}
}
	?>