Magento – How to edit product image size

To change grid 4 to 3
Copy file app/design/frontend/rwd/default/layout/catalog.xml into your theme
and change below code

<action method="setColumnCount"><count>4</count></action>

to

<action method="setColumnCount"><count>3</count></action>

in layout handles catalog_category_layered and catalog_category_default

To increase image size in grid view
Copy file app/design/frontend/rwd/default/template/catalog/product/list.phtml into your theme
and inside grid mode code, change below code
<?php $_imgSize = 210; ?>
to

<?php $_imgSize = 250; // your required image size ?>

finally I found the answer:

$secondimage = "";
$smallimage = "";
$smallimageLabel = "";
$secondimageLabel = "";
$product = Mage::getModel('catalog/product')->load($product->getId());
$getSecondSmallImage = $product->getSecondsmallimage();
$getSmallImage = $product->getSmallImage();

foreach ($product->getMediaGalleryImages() as $_image) {

    $imageFile = $_image->getFile();
    if ($imageFile == $getSecondSmallImage && "" == $secondimage) {
        $secondimage = (string)Mage::helper('catalog/image')
            ->init($product, 'secondsmallimage', $imageFile)
            ->keepFrame(false)->resize(573, 282);
        $secondimageLabel = $_image->getLabel();
    }

    if ($imageFile == $getSmallImage && "" == $smallimage) {
        $smallimage = (string)Mage::helper('catalog/image')
            ->init($product, 'small_image', $imageFile)
            ->keepFrame(false)->resize(573, 282);
        $smallimageLabel = $_image->getLabel();
    }

}